FIRST STEP IS TO MAKE SURE THE MOD IS IN 1MB FLASHING MODE. IF YOU HAVE THE SWITCH CONNECTED THEN YOU NEED TO SET THE SWITCHES TO "ON ON OFF OFF OFF" THIS WILL FLASH THE X3 BIOS TO THE FIRST 1MB PART OF THE X3's 2MB FLASH ROM. IF YOU DON'T HAVE THE SWITCHES CONNECTED THE X3 WILL DEFAULT TO THE FIRST 1MB ANYWAY. MAKE SURE THE FLASH PROTECT SWITCH ON THE X3 IS SET TO DISABLED.
Of course you must have a bios file already resident on a hard drive (C:\Bios) that you have connected to your Xbox. This can be from a previous installation or if you have another bios on your mod enabling you to FTP to your Xbox. There are several tutorials on xbox-scene.com on how to cover this.
by Team Xecuter.