The hardest part is flashing a modified BIOS to an Asus motherboard.
Asus motherboards usually have some protections that stop you from writing to certain regions of the BIOS EEPROM (e.g. flash descriptor, ME region).
It is recommended to use a hardware programmer (such as the ch134a which can be bought for cheap on ebay) and make a full backup of the BIOS before you attempt to write anything to the BIOS chip.
Here are some useful threads regarding the various BIOS locks: