register @ htcdev [dot] com
 just follow on-screen instruction until successfully boot with unlocked bootloader
 flash via fastboot ClockworkMod Recovery for the HTC One X v188.8.131.52[thread] by broncogr or TWRP (recommended) here
Now device is Bootloader Unlocked + CWM recovery + S-ON & ready to flash custom rom. BUT IS HIGHLY RECOMMENDED TO BACKUP YOUR STOCK ROM PRIOR FLASHING CUSTOM ROM.
 To ROOT STOCK ROM with STOCK BOOT.img/KERNEL ,
(i) download CWN-SuperSU-v0.96.zip [thread] by Chainfire
(ii) reboot into recovery mode
(iii) select install zip frm sdcard > choose zip frm sdcard > select zip file as in (i) step above > proceed to flash.