Yea, you definitely want UT2004 in native mode.
http://www.liflg.org/?catid=6&gameid=17 for the updates and addons. The linux installer is either on CD1 or CD5. I think it's on 1 though. I bought the DVD and CD versions.. and the DVD is much mo helpful.
Before you install, as root, enter this:
export SETUP_CDROM=/dev/device of my cdrom