The factory hard copy manual and the cd both cover engine removal. The factory position is to remove the engine/tranny as a unit and separate after they are out, then reassemble prior to reinstallation. There isn't any way I can imagine to remove pistons without removing the engine on a 4matic because of the hardware under the engine. The front diff is in the middle of where you want to be, I believe, and the 4matic pan isn't coming off with the engine in the car. Let me know if you find a better way or if you determine the engine can be pulled without the tranny.