Foreflight have just announced today that they have finally and belatedly integrated the Grand Canyon special rules chart into their coverage. This hard to get sectional (my copy is dated 1998!) was a major defect in their system up to now because it's the only chart that actually shows the corridors.
I've previously navigated using hand created waypoints and a B&W VFR guide published long ago by the FAA that shows the visual landmarks at each end of each corridor. Beware that trying to fly the corridors by VOR/DME is treacherous and the ground features all look the same on the sectional! Having the corridors in Foreflight will be a real luxury!