If you own an LG G3 – we are talking any variant – and are into custom recoveries, ROMs, that sort of thing, then you should probably have already installed Bump. Created by Team Codefire, Bump allows you to boot into a full TWRP custom recovery and flash ROMs as you please, sort of like if you had a full bootloader unlock. As I just mentioned, this should work with all carrier variants (including Verizon’s), you just need to be rooted first (and work through a little adb with a recovery.img).
According to the Bump thread over at XDA, this unlock allows you to flash ROMs much more freely than before, meaning they only need to be compatible with your particular carrier. The particular ROM you are using also needs to have been “Bump’d,” but Team Codefire assures us that “most ROMs you’ll want to download will be pre-Bump’d.”
To get into the full instructions, warnings, etc., we will direct you to the source links below. Feel free to watch the video, though, to get a feel for how this works.