I wasn't trying to get you to buy one. I just figured the wiring diagram would help show you how the wiring goes. As you see in the diagram, you do not wire directly to the alternator. Honestly, if you are struggling at this point, you might want to seek out a professional, or see if there is a forum member near you that can help.
That said... the basic wiring is in the above diagram.. the controller/seleniod is going to go where the USI-160 goes. All the way at the very bottom of the page on the link I provided are 3 diagrams.
How do you plan on activating and deactivating it?