The bluetooth dongle inside /some/ Apple laptops just connects via USB. I think yours is one of them. If you cut the cable in half, you can mount an internal hub to the cable, and wire the other half of the cable (the bit going to the bluetooth module) into one of the hub ports. Alternatively, you can just buy a small USB dongle.

Knowing "guts of computers in general" only helps a little bit with laptop modding/repair. Things are a LOT smaller and a LOT more fragile.