Thanks for the tip, I too had the squeaky noise. I removed the two screws for the plastic trim pieces, and jiggled the assembly to remove both the smaller and larger pieces off. I wasn't sure what surfaces were making contact, but I think the squeaky bit is in fact where the back of the larger trim piece makes contact with the plastic part on the seat rail (located at the back end of the rail). Will post pictures when I can. I put masking tape between these two sections, no squeaks so far. The section can be taped without taking any of the plastic trim pieces off.

BE CAREFUL when putting the screws back on, they're easy to lose! One of mine rolled off under the seat and into the black hole between the car floor and the protective pan underneath the car... luckily I had a replacement screw that fit in its place.