Can it be installed on Mac?

I'm gonna say no. The game works great with Wine (using Wineskin), but the installer does not work in Wine as far as I've tested. So, in a literal sense, it cannot be installed on Mac.

I installed it in Windows and copied the result over, and the game works this way. So far I haven't run into any serious issues with the singleplayer. But the multiplayer doesn't work (trying to look at the Windows shortcut with a text editor showed a launch option that points to the multiplayer(?) library. It might be possible to get the multiplayer working if that launch option is all that's missing.).

Judging from how well the game appears to work in Wine, it seems likely that when AvP officially comes out (ie. sometime after the multiplayer beta end, because that's the whole point of the game being out like this), GOG will put out a pre-wrapped wine version for Mac and Linux.

Edit: I hadn't noticed there was a separate program that launched the game, which handles the multiplayer. That (with the launch options from the Windows shortcut) doesn't appear to work in Wine right off the bat, so multiplayer appears to be out for now.

The Steam version is listed as Windows only. I suppose GOG and Valve will have an identical deal with Rebellion so either both will introduce Mac support or neither.

So atm only SP can be made to work on Mac and MP is anyone's guess.