dl the installer from loki and run it with the cd inserted.
all bonuspacks and other mods are often released as non-umod in zipped format.
http://www.unrealadmin.org has lots of files and tips for serveradmins and since linux servers are most common amongst the unreal servers this page contains a lot of info with value for a linux gamer.
Im playing unreal tournament over 20 hours per week (clanwars and national championships) so I have probably come across any problem you might get stuck with.
Feel free to ask me on IRC : #oxygen on Quakenet.
My nick is usually something with mfx in it (like o2|mfx )