Ive done a remap on a w220 S500 10 days ago and it had a ME 2.1, Kess and Galletto do this ecu both over Diagnostic plug.
Reading is easy via OBD but it took almost a Hour to do, where writing takes 3 min approx. BUT you need to put the ECU into Programming mode manually, in the Kess manual says: Short Pin 3 of the first plug on the ECU to +12 and pin1 with pin16 on the diag.plug.. So you have litteraly a swich wich when you put power on it gets into programing mode and you will be able to write it.
After 2m of wire and 10min of my time i figured it out how to write this Ecu, so it is posible without opening or takeing it of the Car
инфа с MHHAUTO- если кому интересно