Jim,
I've done front end rebuilds on both my 124 and my 126 and I would NOT under any circumstances use that type of external spring compressor on the MB springs. As was stated earlier; these springs pack a huge punch and could kill you if not respected. You really need to get your hands on the recommended compressor. I don't want to scare you off the job; because it's not that tough, but you have to have the correct spring compressor to do it safely.
Additionally, those controll arm bushings are really in there. You need a big hammer and a big chisel. applying some heat to break them free will help, but watch for the burning rubber fumes (toxic). My buddy who is an MB mechanic would actually burn out the rubber with a torch making the pressed in sides easier to bang out with a hammer and drift.
Hope this helps,
Out