Instructions
Go to the "SIXAXIS Driver Download website and download the ".rar" SIXAXIS driver file.
Go to your "Downloads" folder after the download has completed and right-click the ".rar" file to open a menu. Select the "Unzip" option in this menu to reveal the "ps3sixaxis_en.exe" file. Move this file to your desktop.
Plug the Mini-B end of your PS3 controller cable into the port on top of your PS3 controller. Plug the USB end of your PS3 controller cable into an available USB port on your computer. This cable comes with every PS3 controller.
Double-click the "ps3sixaxis_en.exe" file on your desktop to launch the driver. Press the "PS" button in the middle of your controller to turn the controller on. At this point, the computer will recognize your PS3 controller.
Open your "OnLive" program to begin playing games with your PS3 controller.