If you are lucky enough to be able to drill a hole the same size as the OD of wheel in a xx thick board, then: Place wheel in your vice, sticking up from vice 1/2 the thickness of wheel. Set wood piece, with hole drilled in it, down over the stick-up part of wheel. Slide both back under drill press and move around until hole saw (still in drill press after drilling wood) also fits into the hole in wood (while wood is still on wheel). Clamp down the vice, remove wood, remove hole saw bit, install bit sized as Bill says and drill out wheel. If this is not right maybe you can improve on it or it will give you a better idea. I'm thinking this centers the wheel on drill press because you are saying you don't have a center to drill to? Is that right?
