The location of the alternator will vary from car to car but it's driven off the accessory belt so it'll be towards the front of the engine. The regulator on modern MBs is part of the alternator. Two screws hold the regulator to the alternator.
As mentioned above, the MB voltage Regulator album in http://photos.yahoo.com/tabijan
might give you an idea. The pictures are of my 91 300SE.