The HTC One X on AT&T got rooted two weeks ago but that didn’t allow users to experiment with custom ROMs. Unfortunately HTC didn’t offer an official bootloader unlocking solution (just yet) and we’ve tried to see just why they won’t do it. However, this didn’t stop (it never stops) the community and its fine developers from working on a solution and they have found one!

After you get passed all the warnings in bold that scream “you’re doing this at your own risk” you can actually follow a twelve-step walkthrough at the end of which you will hopefully have an unlocked bootloader on your AT&T One X, allowing you to finally do some serious flashing. If you are an experienced user with HEX-editing skills and you know your way around ADB (plus you already rooted your phone) then you might want to look into this. Make sure you read through the thread for feedback and comments even though, given the popularity of the phone, it’s kind of bulky.

Source: XDA-Developers