As you all know, HTC One X (HOX) needs manual boot.img flashing, since we don’t have an S-OFF script yet. Of course, you need unlocked bootloader for any of this. For Linux users, you can install fastboot using:
apt-get install android-tools-fastboot
while on Windows I recommend the Minimal ADB and Fastboot Installer.
To restart the phone into Bootloader, power off your phone, then hold the power and volume down buttons, or you can use adb:
adb reboot bootloader
When you see the Bootloader screen, test it with these commands:
fastboot oem get_identifier_token
If you can see your device and/or the token, try flashing the boot.img from your ROM with:
fastboot flash boot boot.img
and erase the cache.
fastboot erase cache
P.S. On Ubuntu, since I tested on it, you need to run the commands with sudo.