I had to pull off the wood trim-board across the top and then the aluminum strip behind it to get to the seals ('06 Endeavor). Still not real good access, but better than removing the slide.
If you do use powder to act as a dry-lube for the seals, make sure it's not an aromatic-type powder (Baby-Powder, etc). Most of the scented ones have oils in them that will deteriorate the rubber seal material over time. Try to find a 'pure-talc' type.