The Regulator is attached to the window by way of a Slotted Rail that has a bolt on each end that screws into the bottom of the window. The Window has to be about 4 inches down or lower in order to have enough room to get your hands and a wrench up there on those bolts. Also the Slotted Rail will stay on the end of the Regulator arm.
There are 3 bolts or nuts holding the Regulator/Motor assy. to the door. You can remove those and see if you can lower the Window enough to access the Bolts.
Or you can locate the 2 wires comming off of the Motor itself. I used wires hooked to Pos and Neg posts of the battery to make the Motor work at the Connector.
Hooking the wires causes the motor to go one way; swapping the wires cause the Motor to go the other way. The reason is that the Motor does not ground through the Frame of the Car like other compnnents do; only operate the motor through the 2 attached wires.
Also look up the Thread on cleaning the motor Switches. My Window Motor worked when I jummpered it to a Battery but would only go one way after the new Regulator was in place. As it turned out the Switch Contacts needed cleaning. Afte Cleaned OK.
Becarful not to let the Window Drop Suddenly If you have to Tape the Window so it will not Fall all the way to the bottom.
In the first drawing to the upper right is a pic of the Rear Windo regulator. Note the Slotted rail on it.
http://www.detali.ru/cat/OEM_MB2.asp?TP=1&F=123193&M=617%2E952&GA=722%2E120315&cat=318&SID=73&SA=+56194&STRK=02
Here is what I went through
http://www.peachparts.com/shopforum/showthread.php?t=254722&highlight=Extreme