if you have your original red key then you dont need to change your codebox and ecu. you can use the red key to teach the car any other key.
if you dont have your original red key then you do need the matching ecu and codebox from the car the new key came from. you dont need to use the ignition switch, you can simply take the new key's chip out and place it inside your old key, allowing your old key to work the locks (as it alwasy has) and also start the car.
assuming you have no old keys left, you can get one made to fit your locks using the glovebox lock. most locksmiths can do this.
or you could fit that new ignition barrel and live with having one key for the doors and another key for the ignition. personally i couldnt do that, it would drive me crazy.
