Well, what kinda solvent do you have at your disposal?

I'd maybe start with something like brake cleaner, sprayed on a piece of heavy duty paper towel, and just run it back and forth (although isopropyl alcohol would work in a pinch too). Be prepared to use lots of towels.

I dunno about the grease, I'd like to hear about some recommendations myself. The last time I greased the tracks the seat seemed to "slide" a bit unevenly on the rails.