Start the MAME emulator, then start one of your MAME games using the emulator. Press the 'TAB' key on your keyboard to bring up a menu while playing the game. Select the 'Input General' option and you will be shown a list of controls. Click each control once and push the corresponding button on the USB controller that you want to use.
The following profile is now available to download with PinnacleUpdate. The related PIN file has also been attached if you need to manually import.