I finally got around to install an AUX. The article
http://www.xoutpost.com/articles/x3/...avigation.html is excellent for mine (2006 with Navi) vehicle.
Want to share a few notes while everything is fresh in memory,
The original part is _not_ worth $35 becasue you won't be using the connector. find something on ebay/amazon that has a female 3.5mm connector and anything else on the other side. Just check that the other side has 3 wires. You can get away with ~$10 shipped.
Monster cable - instead of it, i bought 3.5 straight and angle cable ( $5
Amazon.com: StarTech.com MU3MMSRA 3 feet Slim 3.5mm to Right Angle Stereo Audio Cable - M/M: Electronics)
Instead of connecting monster to bmw's as described in the article, I secured the BMW cable in the middle compartment. Check picture in step 26 of the article, where X3eme attached excess of the cable in the middle compartment.
Then i drilled a hole to allow the angle connector to plug into the AUX.
Here is the picture i took last night.
The edges look terrible on it for some reason, but it looks fine in a normal light.