Here's an excellent site about propagating from backbulbs.
Orchid backbulbs
I'm trying it myself with a single, small, rootless backbulb from a Miltassia. The bulb came off when I was dividing the plant.
A bulb can really stay alive a good long time if it's not in bright light or dry air. The trick seems to be not to try to make it root, but to wait for it to root... it could be a while. So mine's in a not-too-bright spot, in fine bark that's barely damp, and under a dome to maintain humidity. The dome is a quart-sized clear plastic deli container (had salsa in it).