It could be easy or hard, depends on your hub. If you have wires from the jacks, the 5V line is the red wire, just connect the red wire from the input jack to one of the red wires from the output jack, this is the easy. If you have jacks soldered to the board, it is a bit harder. It would be best to use a meter. The 5v lines to the output jacks are there if the hub is powered on, but you would need to hook the hub to a computer (not the 770) to have the computer generate the 5Volts for the input jack so you copuld find it with your meter. The usb jacks are standard as well. Check this link (it is near the bottom of the page) for the jack wiring which may help.

http://www.usbman.com/Guides/BelkinM...e_assembly.htm

If your jacks are soldered to the board you should really consider using the cable method unless you are sure you have the right lines and your soldering is correct. You could easily fry your hub or your 770 if you get it wrong.