Hi there,
To pair CSW with PS3, you need to press and hold the 2 buttons (ie Select & Start buttons on the Formula rim) near bottom of rim simultaneously for 2 seconds. When properly paired, an orange LED on the Formula rim will light up indicating it is communicating with the PS3.
Here is link to Fanatec's video manual for the CSW, showing how to connect with PS3, and the settings to use with PS3.
http://www.subblackstudio.com/fanatec.html
Hope above helps.
ps: CSW is awesome with GT6 (& GT5 of course)
As stated by previous poster, a bit of trial & error is required to dial in the settings that suit your driving style, and that you feel comfortable with.
Cheers