I would recommend calling Mark at madelectrical.
www.madelectrical.com is the website. The site is a bit out of date as far as prices, but the pbone number there is still good. He is extremely knowledgable about this stuff. I just bought a kit from him last night, and learned a lot in the process. Getting ahold of him can be an issue I have heard, but I got through on the second try. I bought the new system with a trunk mount setup. Take a look at the website. He includes a terminal that you can install in the engine compartment wired to the battery that you can use for a tap point for all the stuff you need.
Russ