Either find/ask for the diagram of the wires or you can just test the wires with a small battery to check what is the LED ones. Once you've identified them you must connect the LED wires to the mosfet VOUT-/+ pins like the voltimeter in the vapoven diagram, in this way the LED will only light when IH is on.
The power wires of the switch must be connected between the + pin of the battery pack and the Mosfet VIN+ pin, as depicted in the diagram.
Here are some pics of my beloved IH which is working fantastically well for 2 years. Honestly I've never touched the inner main switch: is always on. It also has some small switches to disable all color cycling LEDs and voltimeter (AKA "stealth" mode). Has a sliding lid at bottom to access the batteries, and the top lid holds just by pressure. Is activated by pressing dynavap down: there's a button under the glass, isolated to the dynavap with a cork and toothpicks.
I like the enclosure, did you buy it from somewhere or did you make it yourself?