the way we do the bridge, and i'm not honestly sure of any other way to do it, is using a dremel on a stewmac router base with a small router bit, and we literally cut the finish out of the bridge area, but not to the edges of the bridge, they had us overlap the lacquer with the sides of the bridge, so there was absolutely no way to get a "flush" glue seam on our acoustics bridges, same thing with the fretboard, there was no way to get the top flush with the bottom of our fretboards(on the body overlap that is), we did it via the same method... basically you've got a gap of the same thickness as the lacquer, which you've gotta fill with something, and theres no way in hell i'd use epoxy(as others have suggested) to fill said gap, unless you never wanted to be able to do a neck reset, or modify the bridge whatsoever, without destroying the top.