- Flash IMM76K as the IMM76Q update is not a full ROM (instructions on getting your phone to stock IMM76K can be found here - but DON'T lock the bootloader).
- Once on stock IMM76K, re-root and install Clockwork Recovery 18.104.22.168 (NON-touch) following the instructions here under "Obtaining Root Access and Custom Recovery." Then download this file and flash it in recovery.
- Once you've done all that (whew), you're ready to flash JRO03O by downloading this file and flashing in recovery.
As you may have heard, Verizon Galaxy Nexus owners finally have a leaked stock JRO03O Jelly Bean build. If you're already on a custom ROM and just want to flash the radios, just download this file and flash in recovery (thread can be found here - thanks, Snow02). If, on the other hand, you want to flash the latest test build of stock Jelly Bean, you MUST be on the stock Android 4.0.4 build (IMM76Q). To get your phone to IMM76Q, take the following steps (not for the faint of heart):