This trick works fine on the stock ECU as well.
Get a 10mm socket or wrench and take off the negative batter terminal. Make sure it is bent to the side, as you do not want it to make contact with the body of the car or the negative battery terminal.
Get into the car and press the brake for 5 seconds. You will see the odometer disappear.
You ECU has now been reset.
Follow Shivs instructions. Very easy to do. And it works every time.