It is better to flash from a non-windows environment but modding the files themselves is better done within windows due to the programs having a GUI.
Your motherboard manufacturers website will tell you how to flash your bios. It may have a windows and or a dos version of the BIOS flash program. It is better to use the DOS version because windows is more likely to crash than dos. you do not want to have anything go wrong during the flash, it could leave your motherboard dead. This website will show you hot to modify your BIOS. You then need to Flash it into your motherboard with the manufacturers program. Flash means BURN IT into the permanent memory of the motherboard