I had a similar problem with the 300se sunroof - it was an auto controlled by a remote button by the rear-view mirror.
What did I do? Pump some WD40 and it stopped squeaking.
However, due to age (I think), the sunroof dont close as well as it should.
What do I do? Give it a bang from the inside, and it pops right out back in shape.
Hope it'd work for your squeak.
126 tailed by a 203, 129 leading the pack.