carpc in BMW

[...ASH...]

Hi chaps...
Ok, this is what I want to do..
I have an old laptop knocking around and am going to connect it to my e46, I know about cnnecting it to the i-bus but want to know the following>>>
Where can I pick up a stereo connection in my car (I have read everywhere that it's mono)
I have also read that people have used the tape option on their factory sat nav (I don't have tape, I only have CD)
If it's possable to connect to the AV (I can't see any reason why not), how does the computer know not to scroll through the menu's on carx before I have selected AVI (if that makes sence)
THanks in advance

ASH