It's pretty much the same process. Boot the phone in AP Fastboot and run RSDLite on your PC, select the 4.1.2 xml .zip file and go.
I suggest Factory Resetting after to remove your configured stuff......the fastboot just rewrites out the system partitions and doesn't touch the user data.
Got it to reboot after what looks like it installed but rsd lite still says "reboot >> in process." Phone is booted up. Now it says "Please manually power up this phone" and it's on.