I do not know a whole lot about how unlocking the iPhone works, but I just had a crazy idea.

The way I understand it, you need to send an NCK to the baseband in order to unlock it without hacking. This code is based off of the IMEI. What if you changed the IMEI to that of another phone based on the S-Gold2 chipset that you have the NCK code for? Would the iPhone then accept it, and remain unlocked even if you changed the IMEI back to the original?

Probably wont work, but it would be interesting to try.