The dome light is lit when Pin 87 of the Courtesylamp relay is grounded. And the Parkinglamp relay is energized by grounding Pin 86. A diode from Pin 87 of the Courtesylamp relay to Pin 86 of the Parklamp relay, with cathode to Pin 87, will cause the parking lights to come on whenever the dome light is lit.
Its not ideal, but it WILL flash the parking lights once for 1-2 seconds when locking the doors. It will still chirp the horn when the security system is activated and flash the lights twice when unlocking the doors.
Both relays are in the MBEC so, except for being a contortionist, shouldnt be too hard, when the weather warms up a bit.
Any comments from the electronics gurus? Did I miss anything, or is there a better way? This is all just theory, so far.
I dont know if the dealer could program it to flash the lights when locking the doors, but they have a minimum $49.95 charge

to hook up the TechII to do anything.