BT are ya familiar with the "golf Ball" technique of skinning deer? Cutting around the neck and pulling enough skin loose to get a golf ball inside. Tie a rope over the skin around the golf ball and use a come-along, winch, ATV or, even your car to pop the skin right off. Pay attention of course to where you have the deer anchored. Generally a section of 4x4 layed across the rafters of the garage will do. Slow easy pulling should be all that is needed. Also be aware of your overhead garage door as the rope, chain or, even the deer may come in contact with the door or frame. Needles to say your anchor rope or chain should be substantial enough to sustain this type of pulling.
I know a couple guys that pull the skin off as the dear lays on the floor than hoisting for a hosing and cleaning before butchering. Lay the deer on a cheap tarp or plastic sheet to help keep it and your garage floor clean.
I know a lot of what I mentioned is common sense but sure as all heck, some idjut will end up ripping his garage door off or, pulling the roof in, if not, using a anchor rope too small for the job and, slingshot a deer carcass through his car windshield.
On second thought, "box and cut" may be the way to go.