Here's a quick backgrounder. A Japanese software programmer has released Microsoft Windows XP/Vista drivers for PlayStation 3's SixAxis andcontrollers.
Unlike Microsoft, Sony has never released the relevant software to enable its controllers for PC gaming. These unofficial drivers are a stopgap that also unlocks the force feedback function, though compatibility is limited to wired USB operation at the moment.
You can download the drivers here with instructions courtesy of the nice folks from the DCemu UK forum. We've test-driven them on our Lab's SixAxis controller but to no avail, though there are some successful examples in the above-mentioned discussion. No harm trying anyway.