[ROOT] HTC One S

Step 1: Unlock

• Go on http://www.htcdev.com and create yourself an account on HTCDEV.
• Download These Fastboot Files
• Make a new folder on your C:/ drive called fastboot.
• Extract The Zip downloaded in step 2 to the new folder
• Go Here http://www.htcdev.com/bootloader/ and select "All Other Supported Models" and "then begin unlock bootloader"
• Yes, Tick both Boxes, Proceed
• Skip up to step 8 as we have all we need for the first 7 steps
• Power off your phone by holding the power button down for 10 seconds
• Power your phone on by holding power and volume down
• Highlight Fastboot With Volume+or- then press Power
• Plug your phone into your PC and open a Command Prompt.
• (windows XP - Click Start > Run > type CMD in box then press OK
• (Windows 7 - Click Start > type CMD in search box then press Enter)
• Change directory to your folder where we put fastboot files cd c:\fastboot
• Type this into your command prompt window fastboot oem get_identifier_token
• Select & copy the text as per step 9 on the HTCDev website
• Paste your identifier token into the box at the bottom and submit
• You Will Very Shortly Receive an email from HTCDev with a link to the second part of the instructions and your "Unlock_code.bin" attached
• Download the "Unlock_code.bin" from the email and save it to the same folder that we extracted fastboot files to in step 2
• Type this into your command prompt window fastboot flash unlocktoken Unlock_code.bin
• The Display Will change on your phone, press Vol + to accept and power to confirm.

Thanks to bagofcrap24 for this part!

Step 2: Recovery

• Download the Android SDK
• Download the Interim CWM Touch Recovery of Paul or Official CWM of koush (HTC One S)
  (Thanks Paul/koush for the Recovery!)
• Place the CWM File where the fastboot.exe is (Downloaded with the SDK)
• Now open the cmd and navigate to the folder where the CWM File is located
• Now type:
  
  fastboot flash recovery name_of_the_recovery.img
  
  For Paul's:
  
  fastboot flash recovery r2-modaco-recovery-clockwork-touch-ville.img

Step 3: Root

Make sure you are on the stock kernel!

• Now root your phone with SuperSU by Chainfire, thanks a lot!
• Download SuperSU from the end of the thread
• Flash it with the Recovery:
• Power off your device and then hold the VOL DOWN + Power to boot into the Bootloader
• Navigate with VOL and Power to Recovery
• Now flash the .zip:
  
  - install zip from sdcard
  - choose zip from sdcard
  - select the CWN-SuperSU-v0.87.zip file and flash it
  - Reboot now

Now you are able to flash any Custom ROM.

FROM: XDA-DEVELOPERS.COM (THANKS TO TORXX !)