i don't think it's possible for halo either, i know the physics engine isn't anywhere near havok physics, and there's a thousand other small, but greatly important programming details that i don't know of being, or can't be re-created using halo's engine
ASPARTAME: in your diet soda and artificial sweeteners. also, it's obviously completely safe. it's not like it will cause tumors or anything. >.>
always remember: guilty until proven innocent
It's possible, but it'd be hard and probably would need to be done with an external program. And wouldn't be anywhere near as useful as gary's mod in HL2.