We just posted a guide on jailbreaking iPhone 4S, iPad 3 and all other iOS devices running iSO 5.1.1 untehered with Absinthe v2.0, this guide is only for the Apple official version of iOS 5.1.1 IPSW, and not to be tethered jailbroken with RedSn0w. Just the opposite, if you were already jailbroken iOS 5.1.1 tethered on a non A5/A5X devices, just like Corona 5.0.1 Untether, Rocky Racoon 5.1.1 just released by Chronic Dev team for these users.
You need to install this Cydia package on your jailbroken device, to achieve it untethered.
Rocky Racoon 5.1.1 Untether is now available for download in the Cydia/Telesphoreo repository, which is a default source in Cydia.
How to install Rocky Racoon 5.1.1 Untether tweak:
Step 1: Launch Cydia on your device and wait for it complete it’s refresh process.
Step 2: Tap on Search button which is located on the bottom right corner.
Step 3: Type Rocky Racoon 5.1.1 untether to search, you will see a package tap on it.
Step 4: Click on Intsall > Confirm, Rocky Racoon will start the untethered jailbreak process on your iOS device.
After reboot, your device is untethered!
If your device with a brand new iOS 5.1.1 iPSW without jailbreaking, you can follow this guied we posted here to jailbreak iOS 5.1.1 untetered with Absinthe v2.0.