There are times when you don't want the electric step to automatically open with the door. For instance, when street curbs or other obstructions get in the way. One way to do this is to add a second switch in parallel with the door mag switch.
The door magnetic switch is a NO (Normally Open) switch. When the door is closed, the magnet which is located on the sliding door activates and closes the magnetic switch contacts thus in turn closes the circuit. Opening the sliding door deactivates the magnetic switch and the circuit opens.
The rocker switch addition wired in parallel with the magnetic switch fools the step controller that the sliding door is in closed position thus preventing the step from extending.
Fishing the wires where I want the new switch mounted (next to the electric step override switch) can be difficult. I removed the footwell plastic trim (passenger side) to see if I could route the wires from there, and lucky enough there was a hole opposite to where the mag switch is located. I pulled the door mag switch from the pillar and used a heavy gauge solder wire (can't find a hanger wire when I need it) to fish the wires to the opposite side of the pillar. See pictures below.
UPDATE: I just found out that you can easily access the magnetic switch wires by removing the lower sliding door stabilizer reciever plate. Just make sure to mark the exact position of the reciever plate for reinstallation.