(Do this at your own risk, if it doesn't show the right serial number digits don't do it, I am not responsible for your device, so be warned) Jailbreak using redsn0w 0.9.15b3 and then select the 6.0 IPSW, jailbreak it on iPad baseband and use iExplorer to delete Settings.app like Jon said it's under var/applications then reboot using 'redsn0w' go into Cydia add 'repo.iparelhos.com/' download 'Ultrasn0w fixer for iOS 6' then go into the Ultrasn0w repo, it should be added automatically once it's jailbroken and download 'Ultrasn0w' and then it should be unlocked & activated, then go into Cydia search for 'evasi0n untether' and download that and you should have a fully unlocked & working phone + an untethered jailbreak.
Many thanks,
Software