To be honest, I don't know that I've ever even seen an ATI card prior to the Rage 128 era that had a flash upgradable BIOS. Are you sure the IIc card you have even supports that?

I guess the obvious question is "why bother with such an old card anyway"? GeForce MX cards are just as worthless as Rage IIc cards now, and the result would be far more useable.