HK240ZT,
Please forgive my abrupt response, I was not having a great day: not an excuse though. I have no direct experience, but if you were serious about doing this it'd seem to me a part of a much larger project, like building a car where it's important to be able to change wheels quickly. I'd assume the weight benefits to such a system are pretty negligible, especially for a street car. So it'd seem expensive, hard, and to vastly limit your choice of wheels, simply so you can could do theoretically do a 30 second pit-stop, and save a few pounds of unsprung.
Dave