Gave it a try, ended up managing to pull out the plastic tray which surrounds the CD changer, and then took out two screws - but the screws effectively hold the hold central console plastic bit together..

I could not see how to remove the CD changer unit itself!

Seeing as I had to give up on that, is anyone aware of explicit instructions (with diagrams for someone who is nervous about taking his car apart!) or can show me what the IBUS connector looks like in another place which is easier to get to?