I believe that the wiring for the side view mirror turnsignals are already in the door. You only need a mirror with the turnsignal option, and they will plug right into the module. I believe this is true if you have power mirrors already, not for standard cable mirrors that you move with your hand.
This is true for the 2003-2005 years, and it may be true for the 2002 year also. I'm not sure.
If you're interested, check eBay Motors. There are usually a few on there.