From HIFS, you are about equidistant from Epcot and MGM and their entrances are not far from each other. As long as you have a multi-day park pass (such as any hoppers), you can use Disney transportation (monorails, boats and busses) and travel from one park to another by the means applicable to each park. It is fairly easy to get from Epcot to Magic Kingdom and back via monorail. There is a bus from Epcot to MGM. It is also possible to take a boat between Epcot and MGM. Te boat is at Epcot's "back" International Gateway entrance near Great Britain in World Showcase. If you don't mind walking about 3/4 of a mile you can also walk between Epcot and MGM using that same Epcot entrance. The furthest away park is AK and you will need a bus from any other park to get there. Note, you can also drive between parks; parking is $6 "a day" thus if you keep your receipt after entering one lot you can later drive to another lot and park there for no extra charge.
