Hi Rob
You would have to change the internals to accomodate a thicker axle would you not?
I know on my modern Surly hubs, one of them is quick release but to convert it needs the conversion kit which consists of new spacers, axle and bearings. The cost here in the UK is prohibitive as I can buy a new hub for £15 more, suppose it saves me relacing the wheel. This though is just to convert a quick release axle through to a bolt on, is that what you mean or have I got this totally arse about?
Jamie