I tested the cord powering the "Roller Controller" and it connects to the +5v line and the negative line on the power plug.

It is real simple all you need is a dead roller controller for a donor power cord and grommet. 

Please wear safety glasses when soldering and cutting the notch for the grommet. It's not worth risking losing your eye sight.

The cable even has a white stripe on the positive lead. Solder the white striped lead to spot where the red wire coming from the battery terminal connects to the pcb. Solder the other wire ( the one without the white stripe to spot where the blue wire connects to the pcb. I don't understand why the negative wire is blue, it should be black, but oh well.

Cut a notch for the grommet in the top half of the steering wheel case. Put it back together and hook up the power like you would the "Roller Controller" power. Notch should be about .230" wide and .230" deep. And positioned about 4.8" from the left edge to the center of the grommet. This give the mod a clean look since the center of the controller cable is about 4.8" from the right edge.

I used calipers to measure the location and the size of the notch for the grommet.

Here are 2 pictures for reference. 

First is the top half of the steering wheel module laying wheel down on my work bench.
Second pic shows the power cord coming out of the steering wheel housing.

I tested this for about an hour and a half of continuous Turbo gaming. I don't think there are any problems with this, but it is "at your own risk".