Machining wheel mating surfaces to change offset?

[Cloudsurfer]

So heres one for the smart, engineering types:

Is it possible for a good machine shop to re-machine the mating surfaces of a wheel to increase the offset? I have turbo twist hollow spokes on my car (18x10 ET40) that I would love to take to about ET45, so it possible for a shop to take off 5mm of the mating surface to achieve this?

I realize this would have to be done with extreme precision, but I'm inclined to think its possible since the machining of those surfaces are the last step performed in normal wheel manufacturing, and a shop that can precisely deck cylinder heads I would think could perform this properly.

Any input on this would be greatly appreciated.

Patrick