Not that fictional one, of course. That'd be silly. I mean an actual god, capable of death and destruction at the press of a shoulder button.
Turns out you need that less than reliable of things, the Homebrew Channel for the Wii and a couple of Mario Kart-specific cheats. I don't recommend installing it as there seems to be a few broken Wii's out there who's owners didn't install it properly, but at least it goes some way to explaining some of those ridiculous times on the competitions.