I am not sure how much of a shortcut it really is, but when you come down palm parkway to 535, you can go straight and take Vista Blvd into WDW. There are two options from there, you can follow it around the TNT parking lot and eventually loop into the entrance, or take a left on Bonnett Creek which will take you up by Epcot. This could be useful at big rush times over by DTD, but I am not sure it will help much most of the time.