I took a look at the links.. unfortunately, this chipset seems to be at the dawn of the era where the makers got very stingy with releasing information, and I don't see the actual SDK floating around, even though it is referenced. I think you'd need to find that to get anywhere. You can always try asking ATI (good luck with that).
Long ago I either wrote or played with (can't remember) an OpenGL redirector thing, which intercepted calls and resent them. It wasn't terribly hard, but you'll need some docs on what the Rage calls are doing to know what to translate them to. I haven't done any Direct3d, but I suspect OpenGL (especially the older style of it, 1.1 or so) would be an easier target for a wrapper.
I have a couple of these cards and looked through the drivers for a few minutes, hoping to find some function names to Google on, but came up empty.