I would start with trying to find a wiring diagram for the Monte Carlo, or maybe there are specific ones for the seats. For the heater, you will probably need a switch and relay, unless the controls are on the seat itself. I have 2006 Audi seats in my truck. I found the 12V and ground connections on the seat wiring harness and connected them to the truck system. All position controls work because they are integral to the seat. I did't bother with the heater function because I would never use it anyway.
don
