Hi.
Well, this is an extremely complicated project. Maybe this helps you to get a bit further -> http://www.x.org/docs/AMD/R6xx_R7xx_3D.pdf
But I don't know how can you get the card to present the contents of the frame buffer on the screen.
And even if you managed to run the VS, PS kernels on the card, hand writing VLIW code is also not that easy.