cod2 does not have destructable background / scenery on the maps, so as far as i know, this is impossible to do.
EDIT:
let me be a little more specific on this, having something blow up in a map is one thing, my statement was following the request made. to have a grenade leave a players hand and do damage to a house is another, or having a bullet leave the players weapon and make a landmine or a tripwire explode and do damage is also another story, as far as we know, this just isn't possible.