Hi, Firstly, you need to upgrade the firmware on your Ezcan controller.
Secondly, you can replace the OEM Aux light with the D4. There are 4 wire going into the OEM Aux light. You only need the red/green and brown wire. Reg/green being the positive and brown, the negative. BUT...... you are not able to dim the D4 going this way.
Thirdly, connect the D4s to the Ezcan controller and use the dimming function. I presumed your controller does not have the 3 wire dimming plug but you are still able to dim using 2 wires.
Hope this helped.