Anyone ever rigged up a split sliding barn door to an auto opener of some kind? Like a garage door, but instead the doors slide to the left and right allowing entrance to the garage.

A simple Radio Shack with a normally open/momentary close push button then mounted on the other side of the corner bracket, with the switch of course facing the top of the door. And able to ensure that the switch was fully depressed every time the door was fully opened.

This arrangement might work for you, or you might have to improvise a bit. You can mount the switch in the closed position when the door is open.