I would like to know too. The Motorola rep at the Verizon store told me that it could be done (I asked specifically) but I cant seem to figure out how. I guess its back to the store tomorow and hope the rp is still there. If I get an answer I'll post it here!
What I mean is, I want different ringtones to sound when certain people text me, the same way I can set up different ringtones for when certain people call me. So when X texts, X tone plays, but when Y texts, Y tone plays.