Its already on XDA...
Download the file from post # 1 of this thread:
12/24/12 Update x912 - xda-developers
■Copy file from above and drop on SD card (not internal storage)
■Power phone off
■Hold Power and both Volume Up and Down until boot screen appears
■From boot screen, scroll down to ?Recovery? with Volume Down
■Press Volume Up to select it once it has been highlighted
■When Android and exclamation show up, press both Volumes at the same time.
■Then ?install update from external storage? and find the file.
Let the update run, and enjoy.
If you are rooted you can keep root using OTA Rootkeeper.
Before you apply the update:
Run OTA Rootkeeper
Click on "Protect Root"
Click on "Temp Unroot"
Apply the update
Run OTA Rootkeeper again
Click on "Restore Root"