This is how you connect PS3 controller to Mac OSX, PC, etc. when previously connected to a PS3. You will need a Mini USB cable. Overcome your laziness, get up of your chair, and go get one!
A big misconception is that keep holding PS button will reset the controller's pairing. It DOES NOT! From my testings, the controller keeps paring with the last machine it was CONNECTED VIA A USB CABLE.
Here are the steps: