Join Date: Mar 2013
Location: Montreal, Quebec
Well, if you're traveling slow enough (say, normal zipline speeds) I don't think air resistance/whatnot will have much of an effect. Still, you'd have escape velocity to worry about, which should be much less to deal with on the Moon. Plus you'd have no atmosphere to get in your way, so ideally it'd be best to start from there and descend to Earth.
Also, landing on the equator would be messy as you'd be falling straight down, so I think ziplining from pole to pole would be ideal to cut the angle as much as possible for the safest approach. Also, since Earth's rotation cannot be circumvented, having the anchor points pivoting on the poles (360 degree rotations) should work.