Instructions
Turn on your PlayStation 3.
Disconnect your Sixaxis controller from its USB cable. Though the controller is wireless, if you plug it into the front of your PlayStation 3 it will automatically connect via the cable and not through wireless technology.
Press the "PS" button. This is located below the "Start" and "Select" buttons on your controller. This will turn on the controller and automatically pair the controller to your system. You are now using the Sixaxis controller via Bluetooth as opposed to the USB cable.