I tried fishing a conventional feeder with a Polaris float, in a big, exposed Irish lake. I only tried it once - it was like casting out a washing line, and was less effective than either floatfishing or feedering.
I'm not sure why you might want to use a method feeder in tandem with one. Since it's a self-hooking method, won't bites (or rather the rattle of a hooked fish) show up perfectly well on your quiver tip, rod tip or any other indicator at the rod end of the set-up? What will including in a sliding float add?
Have you got some special situation in mind?