you could goto the motor that runs the headlight(each one has an independent motor by the headlight on the sides of the engine bay) and find that power harness for it. find which wire(using a multimeter) supplies 12v to the motor with the lights are turned on. then you would cut that wire in half and wire in a relay that is connected a switch inside the car. DO NOT JUST WIRE IN A SWITCH, USE A RELAY!

how this works is when the relay is not active(switch is off), the wire you cut is half for the motor is connected. then when you activate the switch it breaks that wire, which should cause the motor to move down. i am not entirely sure how the motor on you car is cuz it may not go down when you break that wire but this is a start. again, i am not entirely sure about your car, but this a general idea for one way of doing this. also, make sure you put a fuse(5 or 10 amp) on the wire that gets 12v that runs into the switch.