MB does sell the wiring harness for this. It's mostly a matter of laying out the harness, and tying it in with the existing wiper/washer relay (or adding a new one, if required). You will need to get a new washer bottle as well. Be aware that the new harness runs to the alarm siren, the horns, the headlights (for main operation of the lamps, not just wipers) and the washer pump as well. The part number is 124-543-11-06 and it retails for around $260.