I don't currently have it installed on Linux box, but here is my current idea on how you would go about it.
Make sure that you are logged into the account that UT was installed using, in the dir that you installed it to, there should be a setup prog or a system dir with one in it. Issueing the following should install the umod for you (from the dir with the setup prog) ./setup install <whatever>.umod
Like I said though, I can't currently test that though.
I belch in your general direction.