Another technique I read about somewhere (ETWOLD?) is pushing your tongue against the roof of the mouth. I guess you could take this a step further and rub the tongue on the roof of the mouth and from there you may be able to rub your hands? It's a problem I've experienced myself a couple of times lately and the last time I managed to get my hands together to rub them and got some stability. But it was like they had ten ton weights attached to them and the dream didn't last long.