I bought the Quake packs and I own the Ultimate Quake collection from a few years ago. Which worked like a charm for Quake with Dark Places and Quake 2 with the ultimate patch and KMQuake2.

I've gotten the Mission Packs for Quake 1 working just fine, but Quake 2 looks a little more complicated with all the extra folders. I'm wondering if I can just copy the main Mission Pack data folders over and just make shortcuts/new targets to launch them as I did with Quake 1's? While hopefully having all the new music in wherever they should be as well.

I guess if not, I can maybe just install KMQuake2 again over my GOG installation and go from there? I was hoping to just copy the data folders and maybe the config files around so it plays just how I had Quake 2 itself setup and running. Not sure if it's that easy though.

Go to official KMQuake site downloads page:
http://www.markshan.com/knightmare/

download Official mission pack support file


Some people also recommend making batch files for each expansion / mission pack.

Make a batch file (just a text file with the extension .bat) with these options after the executable name:

+set game xatrix

OR

+set game rogue

Change xatrix / rogue to the name of the expansion.

Or instead of batch files, you can create a new KMQuake2 shortcut for each expansion pack, rename it something like "KMQuake2 The Reckoning", "KMQuake2 Ground Zero", "KMQuake2 Zaero", "KMQuake2 Whatever-expansion-name", then add " +set game xatrix" or " +set game rogue" or " +set game zaero" or " +set game whatever-expansion-folder-name" in the Target line of the shortcut properties then apply and launch the shotcut. ;-)

A bit late to the party, but since this tip was still immensely helpful in 2020... thanks a lot!

Hey! You're welcome!

P.S: As usual, GOG failed to notify me when someone talked to me... -_-'

Since this is already up...
Quake 2 GOG Launcher already have an option to do that easily. You need just exe link files with folders name in execute arguments. But it still require some time to do.
Instead of that go to launcher ini file and replace main executable name from quake2.exe to your sourceport-mod exe file extracted onto GOG installation (or better copy all of this to new installation folder, if you dont want play in GOG Galaxy). Continue use GOG link. Just one tweak in one string.
If you want GOG Galaxy - this way (keep in first installation folder) allow play it as normal "Quake 2".

Music is differ case for each sourceport-mods. Some of them read it from root folder, some require put it to each sub-game folder (like base2\music for base quake 2 game). Should be instruction for that in mod readme.
Or from some threads here.