After further discovery into this wiring, and reading the FSM, I seems as though the computer just senses ground from the switch. So in theory, if I tap that ground AT the switch, I should be able to use it as the ground for the lights. I'll have to try it. And hope it doesn't burn out my entry computer. Which would suck.
The FSM reads:
With rear door LH/RH and/or back door open and the front/rear room lamp switch in the DOOR position, ground is supplied
to smart entrance control unit terminal 3 (with vehicle security system) or terminal 2 (without vehicle security system)
through rear door switch LH/RH and/or back door switch terminal + and
to front/rear room lamp terminal DR
through smart entrance control unit terminal 31
through smart entrance control unit terminal 43 and 64
through body grounds M14 and M68.