If you can get access to a drill press and a couple blocks of wood, it's a snap. Wood block underneath against the half-rim, small block on tire next to the edge of the rim. Press down a little then rotate the wheel a bit, working your way around until the tire is pressed off the upper rim. Remove the upper rim, turn wheel over and repeat. Just be sure the block underneath contacts only the back side of the rim to hold it steady when pressing the top side.

Works for me (if I can find someone local with a drill press). I've even gotten in the habit of carrying the right sized wood blocks along with a spare tire and tube.

Dan Schaefer
N235SP (With more than my share of flats using the crappy Chen-Sheng tubes).