Hello: I just received by mail a keyless entry that was bought by the previous owner of my 1991 500SL. I know it is the correct unit for the car because the physical key fits and works find in the ingition, trunk, etc. but I would like to know how to program the wireless portion for remote locking/unlocking. He had ordered the new remote but had not yet received it by the time I picked the car up so it was not programmed when I got it. Thanks in advance for any help on this.