It depends on how much time you want to put into it.
Here's a decent tutorial some guy put together to use the controller via BT: http://boards.ign.com/Boards/Message.aspx?topic=163284350&brd=8269&start=163295180
For anyone's future reference, here's a link to a video that explains how to set up a wired PS3 controller via the DualShock3 Tool.
http://www.youtube.com/watch?v=-mGA3gcNia0