Is it possible to turn on KillCam in a PRO server. I know a lot of players don't like this but I think it will help with the cheaters.

Not on the client side you can't
Server side I have no idea

I think you can, there is a setting if you are admin, but most likely this will make the server custom rather than ranked.

EDIT: Personally I don't think there are that many cheaters in PRO anymore, you do get the occassional aimbot that likes the mode. Usually everyone is using nano vision, or sniping and camping. I was wondering how some people got K/ds of 10, its not because they are cheating its because they play Crashsite on PRO and camp and snipe without playing the objective.

I used to have some respect for people that only play PRO, but rather than being harder, camping sniper styles noobs it up to infinity. I was playing on one map, which we easily won when I saw 6 snipers all standing along side each other trying to snipe people that went to the crashsite. They like the fact that radar and kill cam don't give away their positions and they can 1 hit without having to aim properly. Someone got a K/D of 10 with very little effort.