Hmm, I guess it depends on the individual car whether the torque converter will hold it or not.(Original post by Sync)
All five of our automatics roll backwards slightly whilst in 'D' on a steep hill. Normally, if I'm hill starting an auto, I'll bung it in 'D' then brings the revs up slightly whilst holding it on the footbrake/handbrake. Makes for a clean getaway and no rolling back.
I've had two old Mercedes W124 autos, and neither of them rolled back.
Here's all you have to do