Sam method will not work anymore as apple patched it, unless you saved the activation token then you could unlock it still.
4.12.01 is at this time unlockable by anything in the market, if you preserved a baseband from a previous unlockable ios baseband then you can make custom firmware and still be unlocked on the older baseband, if you did not save the older baseband then your just like millions of others like myself who can't be unlocked right now.