for starters, you would need flashbios 3.0.1 to flash hacked bios to your X3CE since your 1.6 xbox version has issues with flashbios 3.0.3. Next is you need to download hacked Xecuter 3 bios and version 3029 is the latest. After dl the rar file, you need to extract it and you would only need a file named X3 3029 v16plus.bin to flash your X3CE.
For X3CE, flashbios v3.0.1 is on banks 1234 (on on off off off) and also your backup bank.