This solution was created by timschuerewegen. We have only packaged it for your convenience. He deserves all the credit for it!
Before you start make sure you have BSD Subsystem Installed on your iPhone.
How to Install BSD Subsystem on Your iPhone
Also you will need to have added the iClarified Source if you don't have it already. To know how to do this follow this tutorial:
How to Add the iClarified Source to Installer
Launch Installer by pressing its icon on your SpringBoard.
Press to select the Install tab at the bottom of the screen.
Press to select iClarified from the list of Categories.
Press to select Region Format Patch (1.1.3) from the list of Packages.
Press to select the Install button at the top right of the screen.
Press the large red Install button to begin the installation.
A Notice will appear telling you that this process will patch your Region Format Settings and to make sure you are on the 1.1.3 firmware. Press the large OK button.
Once the install has completed a Notice will appear telling you that Region Format is patched. Also you will have to restart your iPhone for the changes to take effect. Click the large OK button.
You will be returned to the Categories menu. Press the Home button to return to your springboard. Now hold down the Sleep/Wake button for 3 seconds to power off your iPhone. Drag the power slider that appears to the right.
After the iPhone turns off you may restart it and finally set your Region Format!
This solution was entirely developed by timschuerewegen. Please give him your thanks!