How to make your own for GTX video card
I think you want to add the efi part to the GTX 480 by your own and you will get apple logo when booting.
I figured it out and that was not hard.
I couldn't tell the answer directly but could tell you what directions to follow:
1.Find the exactly softstraps or it will show 2.5GT/s or not booting in OS X.
(Open firmware with hex, it located at 0x0058~0x0077 in nvidia rom).
2.Find tools to decompress EFI part.
From 0x0000 to 0x0033 in EFI part,they are EFI standard header.
From 0x0034 to last part, they are compressed EFI part. you have to decompress that or you couldn't figure out how to edit.
3.Compared some mac rom to PC rom. What places was change ?
If you understand what I said, you can modify 9500GT, GTX 285 2GB ,GTX 470 ,GTX 480,GTX 570,GTX 580,quadro 5000 and quadro 6000 for Mac by yourself.
Good luck.