That's a job and a half! I guess he didn't install all the various accelerometers, sensors and associated wiring for a full continuously variable system. It pretty much requires a complete rewire of the entire car, which also involves a near complete strip down.
From M3 tech. document:
"The program is selected using the EDC-K button on the centre console or preset via the MDrive menu and activated using the M button on the steering wheel (for more information, see the MDrive chapter).
The input signals come from two vertical acceleration sensors in the front wheel arches and a third sensor in the rear right-hand wheel arch.
The steering column switch cluster sends the steering angle to the F-CAN. This is transmitted together with the wheel speeds from the DSC to the PT-CAN and evaluated in the EDC-K control unit.
The longitudinal, lateral and vertical accelerations calculated as a result are used as a basis for regulation.
The EDC-K button signal enters the junction box and is transmitted to the EDC-K on the PT-CAN."