1) Install the libusb-win32-filter-bin-0.1.10.1
on to your PC.
2) Connect your controller to your PC with the USB cable. (you may need to press the reset using a paper clip. the reset hole is on the underside of the controller, also make sure your PS3 is switched off and not in standby, as if its nearby it will pick up the controler when you press the PS button)
3) Windows should find the new hardware, let it look for the drivers etc. Once installed run the ps3sixaxis_en
once only and press the PS button on your controller.
4) load up FMS and select 'controls' , 'analog control','joystick interface','calibtare'. You should be able to calibrate the controller now.
5) If it dosen't work press the PS again and run the ps3sixaxis_en
You will need to run the i]ps3sixaxis_en[/i] program every time you connect up the controller.
the link to the files you need are http://dl.qj.net/SIXAXIS-driver-for-PC-PlayStation-3/pg/12/fid/11679/catid/518
Hope this helps