actually I must confess that I'm unable to make such a plugin because after investigation it appears that the CS corpses are not normal entities, they're part of the player class and are handled specially

I was unable to figure out what entity to hide using my PMTools, which simply means that I was looking for something that did not exist. I'm sorry... I really don't know how it is possible to hide a corpse by programming. Are you sure there is no server CVAR in Counter-Strike to hide the corpses or make them fade away ?