Since no one seem to know for sure, I just took a look at it tonight.
Let's just say it was easier than I tough...
Here's how I did it:
DISCLAIMER: ONLY ATTEMPT THIS AT YOUR OWN RISK, HAVE ALL THE TOOLS NECESSARY TO DO THE JOB PROPERLY. ONLY ATTEMPT IF YOU ARE COMFORTABLE WITH DIY PROJECTS AND HAVE SOME SORT OF MECHANICAL EXPERIENCE.
First, working from the hatch, remove the two little button that old the liner to the roof, the plastic part that cover the baby seat fixation and the plastic part around the seat belt for the center rear passenger. Take your time when pulling on those not to damage the liner.
Then carefully pull down a bit on the liner to make just enough room to go trough with your arm(s)
Locate the 8MM nut at the base of the antenna. Using a small 1/4 drive ratchet and 8MM socket, loosen the nut . Don't worry loosing it , it seem to be prisoneer to the antenna base, and remove the base from the antenna. The wire are attached to the base. Shown between my finger is the antenna base, just put it aside...
Last step, unclip the two little tabs (shown on picture) and remove the antenna from the roof of the car....
Instalation is reverse of removal procedure.