This was pretty easy to setup with the kit I bought from ebay. I payed $67 for a start button, relay and wires. The seller also included a wiring diagram of my car, which made life A LOT easier.
Now the actual install of the button. First find a location to install it. I see a lot of people putting this in place of the cigarette lighter. Personally I need that, so that was scratched off the list right off the bat. Before you even think it, I don't smoke, :-P. Anyhow, I thought it would be nice to move the ignition down to the console and install the start button next to it. Well, the ignition won't be done right away because it's a little more in depth than I anticipated. I have installed the Engine Start Button already and here is the low down on the installation.
After deciding where to put the start button I began to measure and cut the hole. TEST FITMENT OFTEN. I cannot emphasize this enough. It took me about 20-30 minutes to drill and fabricate this hole so the button sits flush and will not move. There is a flat side on the button that keeps it straight and in place as you can see in the pictures.
Now, after you finally get the hole drilled and the button installed firmly you can work wiring the switch and relay. I will get pictures and instructions on this ASAP as I didn't take any pictures of the switch yet.
Once the switch is wired you can start routing the wires to the ignition. Obviously this will be different for everyone as you may not install it in this location. I do recommend that you route one at a time, or use different color wires. I used White so I can easily tell which wires are for my start button. I will be using different colors for my switches to disable the ignition and only allow the S2000 button to start the car. Here are some pictures of the wiring.

Once the wires are routed you need to locate the 2 wires in the steering column. You need 2 wires under here. As you see in the picture below there are a few wires in there steering column. The only ones we need are the solid red (12v constant) and the gray and black (starter) wires. These wires should be located on the LEFT side of the column. Yes, the left side. I don't know why the Focus's wiring for the ignition is located there, but it is. This is another reason why I have not moved the ignition.. Here is a picture of the wiring in the column.

Once you have located the wires (see below) you can then start by splicing the wires. Here are some pictures of what wires to find.
Now I attached one wire at a time and labeled them with some tape. I didn't cut any wires at all, I used some of those T-Taps. (Thanks paulhaskew)
I do not have a detailed picture of the switch yet but I will scan the document I received and this will give you a good idea of how the switch and relay is hooked up.
MORE TO COME......
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This Page: Exterior
Page 3: Interior 1
This Page: Interior 2: Engine Start Button
Page 5: Engine
Page 6: Misc
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