Someone has written some software to make it appear to windows as a 360 pad. I never got round to getting it working fully. There are no official drivers for PS3 pads under windows as you would expect but people do have it working with this.
Search google for DS3Tool for a whole load of info about getting it running
did have some software to make it work, i had to press the playstation button while the software was running. cant remember the name of it now, havent used it since i bought my wheel. http://news.filefront.com/how-to-use-a-ps3-controller-on-a-pc/ thats the one i used