You have 3 serious options:
- Level Designer
- Sound Engineer
- Programmer
Level Design (mapping) tends to require art ability, as you'll frequently have to create your own meshes and materials if you want anything other than a cookie-cutter level. That said, it can be learned as you go and all level designers tend to start rough and improve as they go.
A
Sound Engineer requires a background in audio and it helps to have access to proper recording equipment, a recording studio and mixing software/equipment. It doesn't sound like you have any of that though.
Programmers are the work horses of a mod team. You put in the most hours, everyone turns to you when they want information or something done and you can't show off glitzy PR shots of your work, but you do have a little more control over what features get added to a mod and what doesn't. You don't need to know anything about UnrealScript to start with, but you do need experience in OOP languages.
I don't include web admin here because I don't consider it part of working on a mod. While it is contributing to the team, I get the impression you want to actually work on the game itself. It is an option though if you have the skills.
As a CS student though, I suspect you're probably geared best for programming. If they're teaching you right, you'll have Java and C/C++ experience and that's all you need. UnrealScript is very much like a simplified hybrid of the above and for the basic stuff at any rate, it's easy to pick up. The more complicated stuff like replication can take a bit longer, but you learn as you go. If you want to look into this as a serious option, I'd suggest you start by downloading the UDK and then following Hourences' tutorial to get a basic game running. You can skip the map parts. Then just have a bit of a play around and see what sort of custom stuff you can get working. Once you've familiarised yourself with the engine and the editor, you can start looking around the announced mod teams and see if anyone needs another programmer. We tend to be in short supply, so I don't doubt there are potential slots available. Don't apply for Rising Storm though - I'll save you the trouble there, we already have a full complement of programmers. I suspect some of the other mods though, do not.
http://www.hourences.com/an-entire-simple-udk-game/[url]http://www.hourences.com/an-entire-simple-udk-game/[/URL]
http://www.udk.com/[url]http://www.udk.com/[/URL]
http://udn.epicgames.com/Three/WebHome.html[url]http://udn.epicgames.com/Three/WebHome.html[/URL]
Hope this helps.