Now, I've been considering getting L4D for the PC, but I'm curious as to one thing about it.

I know that L4D's engine is just an upgraded version of Sourc, which HL2 and Gmod use. My question is this; theoretically, could one use the player models compatible for HL2 and Gmod and have them replace the survivors? I play L4D quite often at my friends, but if this is possible, I'd be able to assemble my Zombie Apocalypse Dream Team, which would just be fantastic.

So to the modders out there, could you answer my question, and if it is impossible, is there a reason as to why it would be?