How about taking the wheels to a machine shop and have the center holes bored out? Anyone with a decent sized lathe , or even a milling machine could do it.
On an aluminum wheel that works great, the aluminum is thick and usually doesn't have any kind of reinforcement out at the edge. That's exactly what I did with the Enkei RPF1's on my Duster.
But I wouldn't do it on a steel wheel. The steel rims have a rolled lip on them that adds a lot of strength, and if these are the rims I'm thinking of it would have to be completely removed to make them work. The remaining hole would have a thin edge and could be pretty flexy.
