You must be on 4.2.1 (JOP40D) to upgrade to 4.2.2 (JDQ39) using this method.
1. Download this to your computer -> http://android.clients.google.com/pa...D.de8b8d10.zip
2. Turn off your phone
3. Hold down Volume - and Power to get into Fastboot
4. Scroll down to Recovery and enter.
5. On the No Command Android screen hold Power and Volume + to get to menu. Might take a few attempts to get timing right
6. On the menu select Update from ADB
7. Connect your phone to computer with USB
8. On computer type "adb sideload de8b8d101614.signed-occam-JDQ39-from-JOP40D.de8b8d10.zip"
9. You should then see this output: "sending: 'sideload' 100%"
10. Your phone screen will say System Update or something and it will install the OTA.
Once done just select reboot in recovery and you're done. You can use this method for ALL future OTAs - all you need is the update zip. This works on all Nexus including Nexus 7, assuming Nexus 10 and GNexus.
No longer need to wait for OTAs. Enjoy!
UPDATED FOR 4.2.2