I need to unJailbreak iPhone 4s but save current 5.1.1 firmware before a repair?

My iPhone 4s needs to go to be repaired as there is a problem with a piece of the phone having slid out of place and is now covering the camera lens.

The phone is on Firmware 5.1.1 (9B206) I am using iTunes 11 (which I hate) on a Mac running 10.8.2.

I know if I go into iTunes where I have backed up the iPhone and select factory reset it is going to upgrade the phone to OS6.

My question is what do I need to do now in order to preserve the settings so as when I get my iPhone back I will be able to return it to 5.1.1?

I have downloaded Tinyunbrella 6.01.00 in order to save the SHSHs but I am unsure how exactly to go about this as there seems to be a lot of different settings.

On my phone I have xBackup installed which keeps track of my Cydia apps.

Can someone please tell my what I need to do now to ensure I can restore my iPhone on its return to the current setup and firmware?