The quake2 package will automatically pull the best available Quake2 engine.
commercial game data
Game-Data-Packager can be used to automate the installation of the shareware & full game.
alternative data possibility
Quetoo is a "quake2-compatible game" - http://jdolan.dyndns.org/trac/wiki/Quetoo word on the street is this contains critical security fixes to problems that exist in the above. Rumour is it's dead upstream, but the timeline seems to be updated...