In my W140 (S600 coupe) the sunroof adjustment knob is in the trunk on the left (drivers) side of the car. It's behind some molding but not too difficult to access. I believe you pull the knob out a bit to get it unlocked, then turn it a bit (can't remember if by hand or if you have to insert a small hex key or something). Then try your sunroof, and keep adjusting until you get it into the desired position.

Good luck!

Jay