Best thing I did on my E60 545i was to eliminate the stretch belt by installing a belt tensioner pulley and regular belt. Now belt removal/installation is a breeze. The tensioner mounting boss exists on the front of the engine. Incidentally, my '08 4.8i X5 came with a tensioner from the factory.

Sorry to bump an old thread but it's just to say that the Lisle 59370 as posted on the first page works for removing the AC stretch belt. Did it on an E70 diesel today. The hard part was getting the belt aligned up when reinstalling.

Just FYI, there's supposed to be a special tool to move the crank but I used a ghetto method attaching the breaker bar to one of the four small bolts and forcing it clockwise (counter clockwise apparently loosens the screw). Probably not a good idea but ain't nobody got no time fo dat.