I have one but I'm pretty sure it's got bad input lag. It's also pretty old, probably one of the first ones to come out.
So yeah, looking to buy a PS2 to PS3 Controller Converter if anyone has a spare.
This is currently considered to be the best PS3->PS2 converter you can get.
http://www.etokki.com/iNPiN%20PS2%20to%20PS3%20Converter
Not too expensive. Do you have a stick as well? If not check out the Namco that Rugdoctor is selling for 35 bucks if you want to get yourself a stick setup etc for less than 100 bucks this combo will be a good start.