Tim,
First thing to do is countersink your hinges. Cut half of the width of the hinge into both halves of the gauntlets so there's no gap. Epoxy in the hinge and hold it in place with some C-clamps (one side at a time)
Then you can glue in the magnets one by one. Make sure you rough up the surface of both the magnet and the inside of the gaunt. I used clothspins to hold the magnets in place while the epoxy set up. (be careful as the magnets will want to attract and it can get messy when they are covered with epoxy)
Unless your magnets are stronger than mine, you'll need a backup closure. The hoses off the right gaunt will keep it from opening and falling off (make sure one of the hose connectors is attached to the bottom clamshell)
For the left gaunt (mine is ROTJ with no hoses) I have one small piece of velcro that keeps the two halves from popping open.
LMK-If you have any other Q's.
Ryan