Push button engine start

thanks,
i know the basics of how it works, it's pretty simple actually
i was more wondering if you would just pull the ignition wire from where it currently is and hook that to the switch or if you would just tap that wire and run it to the switch?
i suppose that either way would work, depending on if i wanted to still be able to start it by turning the key or if i wanted to exclusively use the button

i'm hoping that i can dig up a DIY on someone else that has done this just to get an idea of what others have done

thanks though

Sean