According to the readme file it's supposed to just detect it automatically but it doesn't and when I push the Xbox guide button or start it turns on my 360 despite the fact it's plugged into my computer. I download the drivers and the files off of the windows website and even looked at the usb controller settings in my control panel and nothing seems to work. The computer recognizes something gets plugged in when I put the USB in but so far that seems to be the only thing that recognizes the controller.
The press release also said nothing about the game refusing to accept input from the keyboard with certain game pads plugged in. Your lack of wanting to install xpadder doesn't mean that my method doesn't work.