Users rocking the AT&T variant of the HTC One X may be feeling a little left out of the HTCDev party right about now, given that the device cannot be unlocked using officially endorsed methods. Luckily, however, the developers here on XDA hate being locked down just about as much as they hate stifled innovation. To that end, XDA Senior Member grankin01 has come up with an easy-to-follow guide that will take you through the steps required to obtain HTCDev unlock on your AT&T One X.
The gist of the workaround is that you first dump an image of your /dev/block/mmcblk0p4 partition. After that is done, simply open the file in a hex editor, look for a certain offset, and modify the CID to read as the Rogers variant rather than the AT&T variant. After this, you’re a few simple adb commands away from dd-ing the modified mmcblkop4 partition into place. Once that is done, reboot to bootloader, verify that you’ve indeed changed the device cid using the fastboot oem readcid command, and then proceed to use the standard HTCdev unlock method.
Those interested in unlocking their AT&T HTC One X should head over to the development thread. Proceed at your own risk, though. A few missed keystrokes could land you a seriously saddening paperweight. Great work, grankin01!
[Big thanks to XDA Forum Moderator Red5 and Moderator Committee Leader NotATreoFan for the tip!]