That's a really great way to melt your OEM switch.
I'd suggest that you use the wiring to your headlamp (specifically your high-beam, in this case) to trigger a relay feed directly off a fuse block off your battery. You'll not only get far superior electron flow, but very likely brighter light with less wattage consumption.
OEM units are designed to pass the bare minimum current, and adding an additional set of lights is a great way to overdraw your wiring's amperage rating. That results in heat, which generally results in a gooey switch (which is un-good by all accounts). You've got a great idea, but I'd hate to see a failure that could be easily avoided (and turn out better by slightly altering it in the long run).
Actually, that is what I did. I just may not have esplaned it thoroughly.
The Piaa lights are powered by the relay that came with it, through my Blue Sea fuse box. I started with original Piaa switch then wired the relay power wire to the high beam switch, still running through the relay and the Blue Sea fuse box.
It works great.
