i think the pad on your doors is like a remote-not directly conected to RKE brain/computer, if thats the case im sure you could mod a factory remote to work with keypad system..though you would have to find place to put the pad itself, cutting the door would out of the question of me.. i think the next step would be the smart key system, im sure that this will be hitting the aftermarket soon.. while near the car it remains unlocked, then as you walk away it locks itself.. a hole lot of cool