Yes. It could be written on a MKWii iso instead of using an ocarina code.
Following procedure will make MAC spoofer permanent on your MKWii ISO without using Gecko OS or Ocarina:
1. Open your MKWii iso using WIIScrubber or Trucha Signer
2. Extract 'main.dol' located on 'Partition 2 - DATA' to Desktop
3. Open 'main.dol' using a hex editor (Hedit, WinHex and so on...)
4. Search for "7F83E37838A00006"
5. Change '06' to '03'
6. Save 'main.dol'
7. Replace 'main.dol' on Partition 2 - Data with your hex-edited 'main.dol'
8. Save ISO
9. Enjoy your MAC Spoofed MKWii version
I didn't test but it should work. Beta testers are welcome.
If it works then it could be done on EVERY game of EVERY region.