Well, to flash it, is like 100% illegal if you really want to know
To flash it, you need the Radeon DDR rom *if you have a friend with a radeon, tell him to dump his ROM onto a disk* then use the radeon flashing thingy, and flash it just as you would flash your motherboard's CMOS.
I would recommend JUST overclocking, and disabling HyperZ though. That way you're not breaking the law by owning the Radeon DDR ROM, you're just making your warranty invalid
I had my Radeon LE flashed w/ radeon ddr 32mb bios, and o/c'ed to 187/187. Use a program such as Raid-On tweaker. It's the best one, and use Humus Recommendations to get the best performance.
Hope this helps!