Talented hacker grankin01 from XDA-Developers has come up with a way to make the AT&T HTC One X blootloader unlockable via the HTCDev website. It’s a very simple process, but you need to have a little bit of know-how to complete it and have the One X rooted (not the same as bootloader unlocked!)
From the looks of it, it seems the unlock involves tricking the device into thinking it is a device from Rogers, which is unlockable.
For those brave enough to have a go, go to the thread here.
(Credits to sk806 for the photo)