What? Pretty Much every UT/unreal filetype is able to be used on a mac, and i should know, iv been using unreal since it came out, and same with UT for mac. If you cant use umod files, use the umod installer(on the CD). Also, if your getting just the map files(.unr) or texture files(.utx) or system files(.u, .ini, .int) just make folder for them..
like make a map folder in the same folder as the UT app is in, named Maps, and put all .unr files in there.. ect ect
Textures = .utx
maps = .unr
Sounds = .uax
music = .umx
cache = .uxx
system = .u, .ini, .int
email me apheleon@home.com if you need some more help about this.