If your car is prewired for a cd-changer you will need to buy a new trunk liner for the left rear. You'll also need to purchase a new storage bin since the size of the compartment does change.
The changer btw goes in the drivers side rear. You'll see the harness wrapped in a cloth type cover with velcro.
You'll need to buy at a dealership and while you're there they will tell you what is needed for the install. If you cant find the parts, PM me.