I stole the idea from a neighbour who put a little video on Facebook, so I guess it's alright if you steal it from me.
The wheels are depth guides, but they are set too high if I've rotovated the ground first. When the ground is soft, the wheels dig in too deep and so the hiller scrapes up too much dirt.
If you make the cross-piece that the lift arms hook to, about four inches shorter than other three-point-hitch implements, then the hiller will follow you better. Mine swings the opposite way when I try to correct when I drift off centre with the tractor. If I drift off to the right, and quickly veer left, the hiller momentarily veers further right, taking out a few potato plants. --- And anybody looking over the fence at the whole operation, will wet their pants with laughter. You don't want that.