You would need to figure out what 4 pins in that connector go to the USB ports, and somehow splice those off to the internal card. They should be the same signal, but the definite source is going to be the motherboard manual. For Shuttle XPC boxes, the motherboard is usually an FNxx part matching the case it came in. So if you have an SN51G system, the motherboard would be an FN51. Search Shuttles site for it, as it should have the pinout of that 10 pin header.