yep, install unreali as normal. setup the directories for inf to look for the unreali stuff in the infiltration.ini. or you can just copy the maps, music, sounds, whatnot into your ut directories.
under core.system or whatever add this
Paths=c:/unreal/Maps/*.unr
Paths=c:/unreal/Music/*.umx
Paths=c:/unreal/Textures/*.utx
Paths=c:/unreal/Sounds/*.uax
then to start it type this in the consol. openvortex2?game=infgametypes.infg_coopgame
there's also a command line to start it multiplayer to.
i'd also suggest adding a toggle to fly and god. there's a few places where you won't be able to run far enough or have to jump from something. there's one map that won't work. it's that really cool super foggy one. it'll just crash. there's no way to save. so just make a not of what map your on and restart it when nessisary. and the translator won't work either.