This may not be that easy to do. I don't know the specifics of any particular vehicle, but I believe the switching is integrated with the vehicle's computer system. Switches nowadays aren't necessarily directly connected to the devices they control. The switches and devices are connected to computer modules, in this case probably at least a driver's door module and the body control module, which communicate via serial signals through the vehicle's communcation bus. The memory function would be part of the body module.
I have the manuals for the 2005 GM pickups that I could look at to verify this. However, I'm away from home and won't have access to them for a while.
