Insert the provided 5V adapter into the accessory socket (lighter socket), and open the glove box door.
Plug the power injector USB connector into the 5V adapter. Plug the 30-pin A2DP receiver into the power injector. Plug the power injector into the custom AMI AUX cable.
Finally, plug the custom AMI AUX cable into the AMI socket in the glove box.
Close the glove box door with the wire exiting the left hand side as pictured.
These installation instructions depict an A4/S4. The exact location of the items referenced, and the items themselves may be different in your vehicle.