Greetings, and welcome to X5world.
Here is my experience with the BT retrofit kit from AA -
http://www.xoutpost.com/articles.php?...ticle&artid=26
FYI, the DB25 connector in my 2001 X5 is black, not blue, and was located down in the lower well compartment below the black plastic cover piece. Here's a picture of the connector:
Good luck with the install, you are going to love it