Start by taking the plastic panel off the boot liner where the latch is - then pull the plugs off the inner carpet- plugs are facing you.
Take the rear light covers off
Pull the rear corner peices of carpet off starting from the top closest to the lights.
I used the below to get round to doing it, and i'll be doing it again so will post my own how to later when I go and update the intravee
http://www.z4-forum.com/forum/viewtopic.php?f=2&t=13086