BMW has again made difficult what was simple. The jack pads I have removed in the past were held in place by two screws. On the E90 you need to push in a tab to release them, very likely breaking it (I did). ECS sells replacements that may be easier to use.
http://www.ecstuning.com/BMW-E90-M3-...rior/ES248447/
Rear Jack pad removed (the locking tab was facing towards the front of the car, maybe different with front pad). The center hole in the frame is where the t-hook goes. I used a small pry bar to remove the pad but a screwdriver might have been a better choice.