Originally Posted by Thresh
My guess is it's a combination of running some dos commands, using winflash, and flashing the GPU BIOS - as that seems to be the most confusing but most reliable method for non reference.
It's not a matter of doing the right things, it's a matter of the card actually being ABLE to be unlocked or not. Some can be, some can't. I would search through some of the popular enthusiast forums (xtremesystems, hardforum, overclock.net, etc) to see if anyone has had luck with your model card.
If you have another card you can use to flash the stock bios back on the card in case anything goes wrong, it may be worth a shot to try it. However I would advise against it because of the risk of bricking the card.