You don't really need to ground a power switch, especially in this case, so if you use yours, try one wire to power, one wire to ACC - (the 'accessory' you're trying to power up). Remember, you're only using one wire, you're just interrupting it on its path to the fan (see the circle in the diagram).
However, a lighted switch does confuse the issue - and that's why it's labeled power and acc - any light requires a 'hot' and a neutral, so that's one more layer of complexity in the wiring you have to do. So - if you really want that to work, the leg you're NOT breaking with the switch should have a short jumper to the "ground" on the switch, to complete the light circuit. The "power" should come from the power source, the "acc" should go to the fan, otherwise the light will stay on all the time.