The update is simple to install. You don't have to be rooted, but if you are rooted you will have to backup root with the "OTA Rootkeeper" app since the new root method will not work on Jelly Bean. It has also been verified that you can flash the ICS fastboot in RSD lite to return to stock ICS if you find this early version of JB to be a bit buggy.
To install
-Download the update.zip and the crc file from the source link below
-Move it to your external1
(Backup Root with OTA Rootkeeper app if you wish to remain rooted)
-Boot into recovery mode (volumeup+volumedown+power, then scroll to recovery, the volume up to select)
-Select "update from external"
-Choose zip
Enjoy!
Via DroidRzr.com