Big thanks to everyone giving results, as well as tips and tricks!

Editing my results into the OP now...

tnx,

For developers:

GalaxyUpdater.log

2014-10-22 02:04:45 [galaxy_updater][Information]: Log started. Application version: 0.1.0.456 (2014-09-18 11:34).
2014-10-22 02:04:45 [galaxy_updater][Information]: Operating system: Windows XP 5.1 (Build 2600: Service Pack 3) (IA32)
2014-10-22 02:04:45 [galaxy_updater][Information]: Updater is starting (channel: '')
2014-10-22 02:04:45 [galaxy_updater][Information]: Downloaded JSON ******galaxy-client-config.json
2014-10-22 02:04:46 [galaxy_updater][Information]: Downloaded JSON ******galaxy-core-files-windows.json
2014-10-22 02:04:46 [galaxy_updater][Information]: Update against manifest 'galaxy-core-files-windows.json' complete.
2014-10-22 02:04:46 [galaxy_updater][Information]: Downloaded JSON ******galaxy-client-files-windows.json
2014-10-22 02:04:46 [galaxy_updater][Information]: Remote version: 0.1.0.456, current version: 0.1.0.456
2014-10-22 02:04:47 [galaxy_updater][Information]: Galaxy Client does not need to be updated at this time.
2014-10-22 02:04:47 [galaxy_updater][Information]: Parsed metadata of 2 files
2014-10-22 02:04:47 [galaxy_updater][Information]: File C:\Program Files\GalaxyClient\GalaxyPeer.dll doesn't exist
2014-10-22 02:04:47 [galaxy_updater][Information]: File C:\users\Public\Application Data\GalaxyClient\downloads\GalaxyClient\GalaxyPeer.dll doesn't exist
2014-10-22 02:04:47 [galaxy_updater][Information]: File C:\Program Files\GalaxyClient\GalaxyPeer64.dll doesn't exist
2014-10-22 02:04:47 [galaxy_updater][Information]: File C:\users\Public\Application Data\GalaxyClient\downloads\GalaxyClient\GalaxyPeer64.dll doesn't exist
2014-10-22 02:04:47 [galaxy_updater][Information]: File GalaxyCore/19767106/windows/GalaxyPeer.dll.zip starting download...
2014-10-22 02:04:47 [galaxy_updater][Information]: File GalaxyCore/19767106/windows/GalaxyPeer.dll.zip downloaded...
2014-10-22 02:04:47 [galaxy_updater][Error]: Error while downloading file GalaxyCore/19767106/windows/GalaxyPeer.dll.zip: Assertion violation: month >= 1 && month <= 12 in file "src\DateTime.cpp", line 67
2014-10-22 02:04:47 [galaxy_updater][Information]: File GalaxyCore/19767106/windows/GalaxyPeer.dll.zip starting download...
2014-10-22 02:04:47 [galaxy_updater][Information]: File GalaxyCore/19767106/windows/GalaxyPeer.dll.zip downloaded...
2014-10-22 02:04:47 [galaxy_updater][Error]: Error while downloading file GalaxyCore/19767106/windows/GalaxyPeer.dll.zip: Assertion violation: month >= 1 && month <= 12 in file "src\DateTime.cpp", line 67
2014-10-22 02:04:47 [galaxy_updater][Information]: File GalaxyCore/19767106/windows/GalaxyPeer.dll.zip starting download...
2014-10-22 02:04:48 [galaxy_updater][Information]: File GalaxyCore/19767106/windows/GalaxyPeer.dll.zip downloaded...
2014-10-22 02:04:48 [galaxy_updater][Error]: Error while downloading file GalaxyCore/19767106/windows/GalaxyPeer.dll.zip: Assertion violation: month >= 1 && month <= 12 in file "src\DateTime.cpp", line 67
2014-10-22 02:04:48 [galaxy_updater][Information]: File GalaxyCore/19767106/windows/GalaxyPeer.dll.zip starting download...
2014-10-22 02:04:48 [galaxy_updater][Information]: File GalaxyCore/19767106/windows/GalaxyPeer.dll.zip downloaded...
2014-10-22 02:04:48 [galaxy_updater][Error]: Error while downloading file GalaxyCore/19767106/windows/GalaxyPeer.dll.zip: Assertion violation: month >= 1 && month <= 12 in file "src\DateTime.cpp", line 67
2014-10-22 02:04:48 [galaxy_updater][Error]: Failed to download file: /GalaxyPeer.dll
2014-10-22 02:04:48 [galaxy_updater][Warning]: Updater failed downloading files, continuing
2014-10-22 02:04:48 [galaxy_updater][Information]: Releasing Updater process mutex
2014-10-22 02:04:50 [galaxy_updater][Information]: GalaxyUpdater exited with return code -20: Updater failed downloading files

Your post was a huge help!

Using your information I was able to get the GalaxyClient running, updated the game and also managed to play a little multiplayer! After testing for a bit, it does usually take a couple tries for the client to run correctly-it will launch but gives some kind of error in the console about the game card failing, so I get a blank window. But when it does work, I am able to launch the game and managed to join a multiplayer game twice so far. It crashed after a few minutes both times in multiplayer, but its a start! How long did you manage to play online for?

I'm using PlayOnMac with Wine 1.7.4

Screenshots of the client running and of the multiplayer session browser within AvP.

The installer worked for me, but it was hanging for a very long time. So if it seems to do nothing, be patient and wait for several minutes, it still may start the installation. Also multiplayer works now with no special hacks (besides the d3dx9_43 library to fix the fonts). But it's all a bit fragile, the game does not always start from the launcher and after leaving a multiplayer match the whole game freezes and has to be killed manually.

PS: As nobody joined my test game, is the game hosted locally and you have to open / forward some ports on your firewall? Or is the game hosted on a GOG server when I start it?

It's not the most stable indeed. I haven't played much, basically jumped from a server to server several times and stayed for a couple of minutes, the most was probably around 15 minutes on one of them.

Edit:
Looks like GalaxyPeer.dll and GalaxyPeer64.dll need to be updated but Updater won't work... <sad face>
At least it's possible to extract required parts of URLs from log so one doesn't have to find a computer with Windows.

I don't know what happened... every GOG installer I have used in PlayOnLinux has worked perfectly.
This is the first one for me.

I just downloaded the installer as I always do and then use manual installation to setup the game and install it.
Crashes every time with this error: OLE error ProgID: "WBEMscripting.SWbemLocator"

I want to create a step-by-step guide on how to install and run Aliens vs Predator, but not with innoextract.
That doesn't seem to be a consistent way to install the game.

I hope this gets fixed or updated so I can run it in PlayOnLinux

See this post

It is possible to install without innoextract, but you have to pass arguments to the installer as stated in the above post. I don't think you can pass installers arguments via the regular install process in PlayOnLinux/Mac unless you set up a script. But you can install something else, then copy the AvP setup file into that wineprefix and create a new shortcut or run the setup program by using the command-line environment.

Ok, another way to get AvP running on Wine (POL), this time without Innoextract shenanigans. This time with arguments
provided by silviucc:
We still need to manually make a shortcut and copy files that Updater can't download, but it's not the innoextract mess I suggested the first time.



In POL create a new 32 bit prefix with d3dx9_43, but don't install anything.

Then go to Configure, select the prefix and in Wine tab start Command prompt. In Command prompt run AvP setup with /nogui etc parameters:
> setup_avp_classic_2.0.0.22.exe /nogui /SILENT /SUPPRESSMSGBOXES
Just don't forget to change path to directory containing the installer or to add the path in front of setup.... Installation ends kind of abruptly and unexpectedly but it works (at least after all this I was able to join a multiplayer game so I assume it was complete).

You need to create a new shortcut for the prefix to GalaxyClient.exe and in configuration General tab put these Arguments: /gameId=1207665883 /command=launch '/path=C:\GOG Games\AvP Classic'



Another edit, I'm getting lost in this post:
As from installer 2.0.0.24, the Updater seems to work fine and no copying of dlls is required.


Now, the last thing is that the Galaxy Updater can't download files (at least it fails with these two) GalaxyPeer.dll and GalaxyPeer64.dll so you have to get them and copy manually to /Program Files/GalaxyClient directory. You can get them from installation on Windows machine (Edit: just an example).

I run the game with emulated desktop, so different resolutions don't mess upmy display.



***************************** *****************************
If Updater doesn't work for you and you manually copy GalaxyPeer dlls, please keep them up to date.
***************************** *****************************

Raff from GOG team was kind enough to offer they'll look into logs and maybe will be able to fix downloading issues. Raff also wrote: If I understood correctly it could even affect other players, so please keep files up to date. Check logs every time you see Updater error just after launching game and redownload them every time if needed, please.
***************************** *****************************



I know it still isn't the most elegant way to get AvP running (with multiplayer) but at least there's no innoextract this time. ;)

E: words/formatting

What wine version do you use? I have installed the game (setup version 2.0.0.22) with wine 1.7 (package wine-development) on a 32 bit Debian testing system and although I have gotten several warning and error messages during the installation I did not have to download anything manually (both GalaxyPeer* files are there). The installer also has created shortcuts for the game itself and the galaxy launcher. The muliplayer mode did not work on the first start (launched from the installer), but on the second try. I had not to do anything manually. I'm not sure if GOG fixed something between the two starts or if I simply had to restart the launcher to make it work. Maybe I was lucky. :)

The main problem with the game is the start. I often have to start the launcher and/or the game multiple times before it runs. But when it runs it works quite well. I already have played several hours in multiplayer mode.
Only when I play a long time on the server (clearly more than an hour I think) the game starts to get jerky and I have to restart it. Also the resolution of my desktop is not restored after closing the game. But when you use Windows programs with wine you are used to such minor annoyances. ;)

I just noticed that GOG has a new version: setup_avp_classic_2.0.0.24.exe
The one I have is 2.0.0.21
Downloading now and will report if it installs correctly.

I'm sure there is a way to pass those commands in PlayOnLinux, but will require terminal use.
I can try that as well.

I figured it out.
I created a virtual drive
Copied the setup_avp_classic2.0.0.24.exe to the drive_c
Created a shortcut to it
Added the /nogui /SILENT /SUPPRESSMSGBOXES to arguments
Launched the installer

Lucker. ;-)

Yes, the game doesn't always launch. And resolution is a pain... But, what matters is that things work. Most of the time. ;)

In POL I use Wine 1.7, on a 64 bit Ubuntu 14.04. I'd say that I'm a Linux-illiterate so it's possible that I missed something obvious and that's why I have to find my own weird solutions to problems. And then these solutions create other problems... well, just my luck.

I also found out that Galaxy is bundled with Aliens vs Predator .exe
For some reason I thought Galaxy would be a separate download like Steam, but no... they included it with the download for the game.
Not sure if I like this because they must have modified the installation to extract Galaxy as well and then the game.

But if you install it with the arguments, it will extract fine and then you can launch it from a shortcut.
I hope all GOG games aren't going to inherit this problem

Interesting, thats the one thing I couldn't get to work. The client always opened in an independent window and the game always launched full screen even when I set the configuration to emulate a desktop. I'm using PlayOnMac so maybe its an issue with that instead of Wine.

That's weird. Have you tried to ask on PlayOnMac forums about it? Because it seems rather unusual problem. Well, at least quick googling didn't turn out anything useful that could help.