Ground effect

[Mz3dude]

Lets say you want to install ground effect using 12V neons. You have 2 main choices.

1- wire yourself on the main headlights and
2- pass a wire from outside to inside and to a switch on the dash board.

Now 2 is my best scenario but how do I do pass the wires from outside to inside?

In every car I've owned I wired to the headlights. But it is alot more convenient when connected to a switch (you see a cop, you turn'em off!)

thanks for the help.