The Jelly Bean 4.1.2 OTA Update changes the partition scheme to more closely match the Nexus 4, allowing the use of modified Nexus 4 kernels, which is critical to any modding.
You can go to Settings->General->About Phone->Software Updates on your phone to request an OTA update from AT&T. If you don't get one, you have to wait 24 hours to try again.
If you don't want to wait forever to download the OTA update, you have to use LGNPST to flash the OTA.
Pastebin - LGNPST Installation and Usage Guide
(if the above doesn't work, use the below)
Pastebin - Manual Install LGNPST