The VGA BIOS is the fundamental settings of the graphics card. You can´t access it at all. Some people have succesfully "flashed" their cards BIOS and gotten better performance, others have lowered their performance. No manufacturers release new BIOSes (as far as I know) and you will most likely void your warranty if you try it.
<font color=red>I´m starting to feel like a real computer consultant.</font color=red>