Well I could probably do it but why can't you just use your standard music player? There are several threads on suggestions for how to organize your itunes music. My personal one is Genre: Resort(Disneyland, Walt Disney World, Tokyo Disneyland) Album: Park(Disneyland, Disney's California Adventure, Epcot, Tokyo DisneySea, ...) Artist: Land(Fantasyland, Tomorrowland, Living Seas Pavillion)
Edit: and to add to that, say I made a custom media player for you that was the exact same as the Music app but was designed to only play your disney music, you'd still have to go through your library and set up which songs constitute your disney music