Rooting your HTC One X is fairly straight forward thanks to HTC allowing you to unlock the bootloader. Follow these instructions to root your device.
Head over to http://htcdev.com/bootloader and follow the instructions to unlock your bootloader
Download the Android SDK https://developer.android.com/sdk/index.html
Connect your One X to your computer via USB, shut down the phone and hold the
Volume down & Power button, this will boot the phone into recovery.
Open up a command prompt/terminal app and navigate to the directory you installed the android sdk and use the following command
cd D:\sdk\platform-tools fastboot flash recovery r1-modaco-recovery-clockwork-touch-endeavoru.img
Make sure the
r1-modaco-recovery-clockwork-touch-endeavoru.img file is in the
platform-tools directory. Assuming this is successful, your device should now have ClockworkMod Touch installed.
Shut down the device again and boot into recovery,
Volume down & Power button, you should be be in the Clockwork recovery.
Backup and restore >
Once the backup is complete, select
Install zip from sdcard and select the SuperSU.zip downloaded and copied to your sdcard. Once installed reboot your system one final time.
You should have now an unlocked & rooted HTC One X.