http://forums.d2jsp.org/topic.php?t=75751420&f=136the same thing this guy was asking about.
a line out converter turns your stock head unit output into rca output by tapping into the rear speakers.
tons of youtube videos about this. very basic wiring job that can be done at home if you want.
after that its just a basic amp wiring kit and you're ready to install the amp and sub.