For anyone wanting to use the Hi10 X keyboard connector, along the bottom edge of the tablet, for USB, here’s the pinout:
Assigning pin numbers 1 to 5 from left to right, with the tablet face up and the connector facing you:
1 ground (black)
2 D+ (green)
3 +5V (red)
4 D- (white)
5 keyboard sense
(The colors refer to the standard colors for USB cable wiring).
Pin 5 (keyboard sense) must be pulled down to ground by connecting it to pin 1. When this is done, pin 3 rises to +5V and the USB port becomes operational.
Connecting to the pins can be done with pogo pins, and as the bottom edge of the tablet is magnetic, something can be cobbled together to hold everything in place with something like a couple of small pieces of steel.