This instructions can be applied to your Mac, Windows also Linux OS. However follow the following instructions at your own risk, therefore if there is any damage or brick caused after following the instructions, no one will be held responsible, but yourself. Are you all for it? Then let's proceed!
How to root HTC ONE S On Android ICS For Windows, Mac, Linux
Step 1: Firstly, download the Superboot.zip, once it's downloaded then extract the files within.
Step 2: Make sure your Phone is in bootloder mode. Do so by turning off your device first, then turn it on with the "volume down" button press, your phone will be put in bootloader mode. Then press the power button for the second times to enter fastboot.
Step 3: Extract "r3-ville-superboot.zip" you downloaded from Step 1, then save the folder in a recognized location.
Step 4: Now plug your phone to your computer using USB cable.
Step 5: Locate the folder containing the extracted files. As for Windows OS: Double click on the following:
Step 6: As for Mac, Run the Terminal app on your Mac. Then, type the following command below:
chmod +x install-superboot-mac.sh ./install-superboot-mac.sh
Step 7: Run the Terminal application on Linux computer. Type in the following command:
chmod +x install-superboot-linux.sh ./install-superboot-linux.sh
If you follow the instructions above correctly you should have rooted your HTC one S. However if you have any questions concerning this, you can visit the original thread, and post your questions there.