I have a 2003 TL-S with Navi and OnStar system. Now, I am thinking about installing Nokia Hands-Free Car Kit but I want to do it right. I am wondering whether it is possible to connect this Car Kit to existing speakers, microphone and radio mute that come with OnStar. Well, at least I want to connect it to existing speakers in the car. Technically I understand it can be done, but any of you know how exactly I can do it? Any instructions? Thanks.