Have a look at bulldogsecurity.com. They have rudimentary tables of the locations and colour codes of the wires to pick up, for many models of car, including Mercedes.

You need to verify the wires on the real wiring diagram. I found them fairly accurate for the 1990 Jag, and am about to do the 1989 190E. I have not tried to do automatic window up or sunroof close.

They also have a diagram for the Mercedes vacuum door lock system, which requires that the alarm be set for a longer lock/unlock pulse. My alarm system requires a pair of relays, wired into a unit which should be easy to install. (I have made the module, but have not yet installed it.)