honestly, I can't think of a way to do it. Dlink has one USB adaptor that apparently has mac oS X drivers for it, but to my knowledge, that's the only one. You could always try downloading those drivers (one site I was looking up said they were made by the maker of the chipset, ralink), but I doubt it will work.
The best solution would be to just run ethernet cables if possible, or get your hands on an ethernet bridge. That's all I can offer.