Yeah, it looks like another _setup function is in order. Make sure you keep any attributes the original via_generic_setup function has (you can just copy the definition and change the name).
But it is kind of hard to do this if you don't know tech specs. Hope you have some luck finding things out.
Edit: and if you get a function to work, I think linux-kernel would probably be interested (assuming someone else doesn't beat you to it). You should probably send off a patch against whatever the latest 2.5 kernel is, though. Maybe sending another one (against 2.4.20-prewhatever) to Marcelo to get into 2.4 would be good, too.