I wouldn't do it...
I considered doing the same thing on my 525i but after taking a good look at it, there are so many "floating" suspension components that I didn't get a warm fuzzy feeling that the differential mounts were sufficiently robust to lift the car.
Not being experienced with bimmers, I snooped around a bit and learned each one has specific "lift" points and "jacking" points.
The jacking points in the rear are typically under the running boards just ahead of the wheels. The lift points vary from car to car depending on the frame configuration.
Perhaps they are identified in your owner's manual. (I don't have one...yet) If not, maybe do a post search on "lift points for a 528"
Hopefully someone with a 528i can advise you.