This should do the trick. Restart your computer and steam should now detect your PS3 controller as an Xinput compatible controller without having to load a driver every time you log in.
You should no longer have to load a driver every time you log in in order to get your PS3 controller to work with your games!
This will make it easier to turn your PC into a dedicated SteamBox so theoretically you never have to see your desktop if you want to boot directly into BPM.
*Note* I don't have blue tooth so I couldn't test the pairing, but there are instructions to pair the PS3 controller in the Link as well.