A usb device (such as a teensy++, a bumble-b or an atmel chip+vusb) can talk to the PS3 as an “unpaired” sixaxis.
I think it has to have the following characteristics:
- the same vendor id and product id
- the same hid descriptor
- after a small delay, the device sends a PS3 button press
- when the PS3 requests for the bdaddr, reply with the bdaddr we want to pair
- when the PS3 sends its bdaddr, reply “ok”