I'm looking into adding a 3.5mm audio input to my car for my iPhone, and I really have no idea where to begin, so I was hoping you guys could help me with this. I currently have a 2007 Toyota Corolla that has a 3-disc CD changer along with the basic AM/FM radio. All I'm looking for is a simple 3.5mm cable to connect my iPhone to the stereo, so that I can listen to music and GPS directions through the speakers. Is this a simple type of add-on for a car like this, or more of a bigger project? Is it something that can be done in a dealership or at home? I know next to nothing about cars so any help or advice would be greatly appreciated.