Well after trying the search function, a few hours of Google, and a few more of tinkering, I think I just need to ask someone about this one.
So I tried buying the add a circuit, stuck a 5 volt fuse in it, and then swapped it for the fuse that powers one of the power sockets in my car, and then attaching the battery + wire from the 500s cable to it.
Then I attached the parking break wire to a bolt that goes through my car's frame, and starting the car up.
The 500 didn't recognize that it should have been plugged in, and I know that socket in my fuse box is live, so then I tried a