From what I read on the fine print, will not work on X5's with a CD Changer, NAV Systems, DSP, or Sattelite Radio.
Here is the print:
Only available for model year 2002, 2003 and 2004 BMW3 Series; Z4 Roadster; X3 and X5 SAV. Not available on vehicles with navigation system, CD changer, DSP cassette player or satellite radio. Installation performed by authorized BMW and BMW SAV centers only. Third-generation iPod (software 2.2 or later) or iPod mini (software 1.1 or later)
Thinking about disconnecting my CD Changer for this unless someone has other options.