Okay, here's a bit more. I would find the always hot +12v wire that is attached to the light switch. Tap into into it and use one of the following receptacles with the above memory saver. I would simply cut the two wires going into the aftermarket accessory socket. Attach the tapped wire from the light switch appropriately and make myself a ground to the frame in the dash and attach it to the other wire.

Probably cleaner and better methods but I've got a lot to do elsewhere..