That was wrong tool altogether in my earlier comment; it's for removing/installing the rear wheel ball joint. Sorry.
I did a little more digging and it looks like there are two different tools for the three bushings; one for the forward two and another for the rear.
BMW Rear Differential Mount Bushing Tool Set E46 E85
BMW Rear Subframe Differential Bushing Tool Set E46 E85
It's too bad the manufacturer doesn't have both sets of plates and cups in a single kit with one threaded rod. I wonder if getting a universal bearing adapter/puller kit would work as well as the BMW-recommended tool. It would definitely be easier to find.
FWD Front Wheel Bearing Adapters