It doesnt work if you have the CD player in the back of your trunk. You'll loose the NAV voice. Solution is to rewire from your CD player...

For those stumbling on this thread a little additional info.

The rewiring solution is found here btw: ***RESOLVED*** 03' UK MCS with HK and Sat Nav, want to get TMC to work? - Page 2 - MINI2 - MINI Forum

Visual comparasion between Alpine and Siemens is found here: Factory MP3 Headunit part numbers - MINI2 - MINI Forum

On a side note I think it may be related to the joining of A5+A6 and pin 9 and pin 15 in this instruction manual http://www.motoringfile.com/howto/CD%20Changer.PDF (page 9 and 10) but havent tried it.

Currently I'm running my Alpine with the MKIV, as a result I have no audio on my cd changer on my right front speaker so basicly not using that. Need to put the MKIII back in to see if I didnt damage anything with trying different wire combos and then work forward from there again

This issue seems to be related to older R53 models with navigation, CD changer and H/K for newer R53's its drop in and play.