I actually spoke to this owner a few months back when i was interested in the same thing. He said the retractable cover was actually removed and rebuilt on the inside to pop on and off to "hide" and "show" - no idea how sturdy it may be.

Also, he said when you remove the retractable cover it exposes enough room for a single din radio to be inserted - he said he used a modified bezel and altered the frame.

Also, he kept the power to the factory radio alive so when the cover is on the new radio, it looks factory. Pretty neat concept.

Similar (or maybe same?) setup here:

http://www.xoutpost.com/x5-e53-forum/...m-fotos-3.html

Hope this helps.