You might have some luck with star polyps, i`m sure somehow it could be done. I`ve heard of people cuttiing off the dark purple base and attaching it to glass.
SPS, xenia, mushrooms, zooanthids, encrusting gorgonian, anthelia, star polyps, all grow on glass. The coral doesn't know the difference between glass and rock. It is just a new place for them to inhabit.
Going to give it a shot with tonga mushrooms. they match the coralline on rocks to well so they dont stand out as much as I would like them to. I got him pinned against the overflow with the suckion cup contraption from a powerhead. I will wait a few days then move his buddies over.