What's the difference between the servo cable and the network cable? Can excess servo cable be used for a network cable or is there something special about it? I know the power wires are slightly bigger.
The installation guide says the power/ground should be 20 gauge for the servos, while the rest can presumably be 22 gauge, so it should be fine for network cabling.
On the other hand, I don't think the servo harness uses all 9 pins/wires.