An idea for you (did this with one of my mares to get her to stand) but you need a round pen.
I take a rope, like a lead rope or whatever, doesn't need to be anything special, drape it over the back and down the side (like a cinch would hang). Grab it and bring it up like you would cinching. When the horse moves, drop the "cinch" end and send him off. Make him move his feet. he can stand when he is being "cinched" up, but if he chooses to move, I would make him move and make it more work to avoid the cinch then it is to stand still.
I hope that made sense as I suck at explaining things I can do and picture doing.