Help installing a kill switch on 79-Johnson 150

[papaknight]

I have a 79 Glastron with a Johnson 150 and I purchased a Sierra MP28870 2-wire kill switch or ignition interrupt. Unfortunately, there are no instructions on hooking up the 2 wires. One is a black ground and the other wire is black with a yellow line. Can anyone help me with where I would hook up the wires and if you have any suggestions on the best location for the kill switch. Thanks!