Had a bit of a time trying mine (admittedly, I got myself in the boat I found myself sinking with).
Figured I'd take the plunge, and go for 4.2.1 R3...downloaded, so I thought. Made a Nandroid using the Toolkit that I've come to love and cherish. Went to install the new load, but it wouldn't take, since I was still on Clockwork 5, so, I downloaded the updated Toolkit (v1.6), and then updated CW to 6, having recalled that I had read something about it. And therein lay my downfall...because while it DID load the new ROM for me, it errored out immediately upon bootup, with the gapps force closing, and then setup wizard unable to start (I loaded the new load from the IRC link, and the 4.2 apps I think from the Sourcery page). So, I figured ok, I'll restore. But...the 1.6 Toolkit doesn't use CW recovery any more...so, ok, I still have a copy of 1.5x somewhere, so, I fired that up...but since 4.2.1 installed that /0 folder and moved everything...the restore wouldn't load, because it couldn't find the file from within recovery.
Was FINALLY able to restore my Nandroid, after copying the Clockwork folder from /0 back to the /InternalStorage directory, and then rebooting into recovery and restoring. I JUST now finished copying all files from the /0 back to the regular directory, and deleted the /0 folder completely. Honestly, I am slightly nervous about powering off my phone now lol.
Still trying to figure out what went wrong...
And if anyone has any suggestions, or step-bys for the latest updates, I am more than all ears.
And just for completedness-sake, Before I tried, I did a TiBu of apps/system data, created it's .zip. Wiped data, cache, and dav. installed the ROM, and gapps. Seemed pretty straight-forward...and I busted it. lol.
(phew. restarted the phone after deleting /0 and all seems well so far.)