The easiest way to get the aftermarket system to operate your locks is to tap into (not cut) the two wires that connect the drivers door switch to the central locking relay. This simply duplicates the circuit in the door causing the car's original relay to operate all the motors. The UNLOCK wire is Black with Green stripe and the LOCK wire is Black with Yellow stripe. They are pins 5 & 6 at the miltipin connector under the dash next to the doorpost. A momentary grounding of one wire (negative trigger) will cause the lock/unlock action.

On '89 and later 700 cars, you cannot use the passenger side actuator on the driver's side and retain the original operation - the sensing switch for the key/lock button movement is inside the actuator. In fact, that's the switch connected to those two wires leading to the locking relay.