Need Help Making COD4 Trouble In Terrorist Town Mod (TTT)

Ok, so basically im making a TTT mod for Cod4. firstly, i would suggest you add me on skype because this could get confusing, and hard to explain.
skype: ericf042

so im currently stuck on code where i want the game to randomly select the terrorists, randomly select the innocents, and the same for detectives. I cant find a code for randomly selecting or going on chance, or percentage... I want the game to completely randomly select a player, by chance, again... completely random. so basically what i want is a peice of code which lets me randomly select something.
e.g
40% chance goto thread Terrorist();
20% chance goto thread detective();
40% chance goto thread Innocent();
i hope you get the idea. thanks for reading and please post a reply :)

edit: these are the %'s
25% of the population or one Traitor for every four players.
12.5% of the population or one Detective for every eight players.
The Innocent are the majority (normally 75% of the game's population

Wrong section buddy.

@ericf042
Ever heard of the Hide n Seek mod for COD4? It randomly picks someone to be the seeker. Look for the mod on Google or somthing

Thanks for the reply but i cant seem to download the mod, and open it in ff viewer, if you could be kind enough as to find the _rank.gsc file in the mod and send it to me, or somehow find the code, i would be so greatful (credit will be given)