For those of you who want to run the latest CM11 ROM Snapshot M10 on your AT&T One X (which I highly recommend as it makes your phone 3 times faster), you will need to update the bootloader on your AT&T One X.
The best way to do is to get S-OFF then run the RUU. By getting S-OFF on your AT&T One X, you will be able to flash the RUU without wiping your internal storage completely.
After getting S-OFF and running the RUU, you can re-install the latest TWRP recovery using fastboot then install the latest CM11 ROM Snapshot M10.
So, here’s the steps: