Unlock iOS 6 On iPhone 4 And iPhone 3GS Using Ultrasn0w Fixer

Ultrasn0w Fixer for iOS 6 will only work for iPhone 4 and iPhone 3GS users, and supports the following basebands:

• 01.59.00
• 04.26.08
• 05.11.07
• 05.13.01
• 05.12.01
• 06.15.00

The official Ultrasn0w might be updated at some point in the near future, but this Fixer should tide you over until that time. You will of course need your device on a jailbreak iOS 6 (a tethered-only break, at time of writing), with preserved baseband.
Without further ado, here’s the quick and easy-to-follow guide.
Step 1: Launch Cydia, and hit Manage, then Sources.
Step 2: Next, you’ll need to add the iparelhos repository. If you’ve been organized and re-added your sources from iOS 5, then it should already be there, but if not, select Edit and Add, and type http://repo.iparelhos.com before hitting Add Source.

Step 3: Next, download the latest official iteration of Ultrasn0w from Cydia.
Please ensure you install the official Ultrasn0w first BEFORE installing the Fixer, otherwise it will not work properly.
Step 4: Now browse for Ultrasn0w Fixer for 6.0 utility in Cydia. Next, tap the Install button and let Cydia work its magic.