I don't know, because I've not installed one (but I do know it's good, because I know the company well, AND know satisfied customers of the product), but I would assume the necessary connections would be as follows:
Power (accessable in the trunk)
Ground (accessable in the trunk)
remote (accessable in the trunk)
tap speker leads for signal (accessable in the trunk)
Keep in mind this is the best "simple addition" of bass, not the cheapest or most cost effective. I definately recomend it, but you can get better for a similar amount, it just requires a more labor intensive install.