Team Fortress was never developed for Quake 2, due to the fact that Valve snapped up all of the TF devs. There IS, however, a Team Fortress look-alike for Quake 2 called Weapons Arena. I found the home page with the downloads page and the install handbook. It seems to be easier to use this link to download the files, however.

In theory, one would download wfq2client.zip and wfq2maps.zip, unzip Weapons Factory to the proper quake2 dir (quake2/wf), and the map pack to quake2/wf/maps, and then run:

maqii +set game wf +map acid3

... When I do this, however, I get what looks like generic Quake2 running the WF map. Sigh.

EDIT: I guess the problem is that I only have the client files. I need to test this with a WF server.