I used a tranverse rod cord control
that I found at Home Depot and a standard closet track.
It took a little doing, but after removing all of the plastic clips that are used to hang the drapes on, I was able to attach the moving end of the mechanism to the doors. When you pull the cord, the doors open and when you pull the other cord, they close.
Mine are a little wonky at the bottom because I have to leave it open for the puppeteers -- something that shouldn't be a concern for you guys. I think I have an idea on how to make a tack for it that won't get in our way. That should stabilize it.
I made the doors because my doorway is only 16 inches wide and about 3 1/2 feet tall, but you guys should be able to use real doors.
I think this is the way New Voyages does it (I used to chat with one of their builders), but it could be that their mechanism is based on a traverse rod. Mine, being smaller, might be able to use the standard pull string.
Hope this helps!