Rick,
I've added two switched circuits to my car, one for trailer lighting and the other for my GPS. To make the electrical connections, I used the following products:
http://www.amazon.com/gp/product/B001QRSBY8/ref=oss_product
http://www.amazon.com/gp/product/B001QRSBW0/ref=oss_product
In the fuse panel that's inside the left edge of the dashboard, there are several unused fuse locations that have a connection for power, but no connection for an outgoing circuit. Using a test light, it is very easy to locate switched circuits. As I recall, rows of fuses are either all switched or battery power. Just be careful not to pull too much power from these connections. Since you don't know the capacity of the wire you're using, extra care is required.
Since I installed my trailer wiring, I learned that if you remove the battery, you can gain access to a through-firewall wiring grommet that you can use to run a wire from the main power panel under the hood to the inside of the car.
