Surely this should be possible without opening the system up? What if you go into Device Manager and check all the USB hubs that are listed. In the Power tab it tells you what is connected or there is free ports available.
From my understanding you should have 2 USB ports which are the external ones on the TR, 1 will have the Motion Eye, 1 for the Memory Stick reader (USB, yeah?), and then if you have something else then that could well be a Bluetooth module. I haven’t got my TR yet but this is how I imagine it is configured. Is there anything else USB on the TR? I cannot think of anything off the top of my head.
Still if you want to take it apart, go ahead. If you do can you get us some really good pictures of the motherboard? I’d like to see if I can workout where the final USB connector is that the BT module would actually sit on. Just as I’m curious, my TR is gonna have Bluetooth in it already.