I had been using the basic technique for quite awhile sans panavise. I have a ribbed rubber tire chock and I lay the stone on the rib that gives me the desired angle. My angle measuring device was made for loft and lie of golf clubs and is accurate to one degree. Once the stone is in place, one hand is on the handle and the other on the blade, just like free handing with the stone laid flat. From this point, all one need do is keep the flat of the blade parallel to mother earth. In this modern world, the old measuring devices aren't even needed as I have the Dual Level Pro iPhone app. As Ray Ray would say, "How cool is that???"
Sorry about the focus. Crappy camera.