Hi lodoss118,
Thanks for the links, basically the registry method is the same we're using, and the other one is the custom EDID method that we've been experimenting with too. Anyway this ATI Custom resolution tool has a feature to reset the driver which is... inspiring

Regarding the AVGA, as it has already been discussed, Ultimarc got its specialized bios directly from ATI so it is proprietary material. I have no interest in reverse engineering it, not now nor in the future.
Considering that the probability of ATI providing us with the information tends to zero, our only chance is to reverse engineer the drivers in the hope that the functionality still exists and it's a matter of exposing it. A task that's certainly possible but unlikely in practice for people with normal jobs & family.