Never seen a visitor message before - interesting...
Anyway, the air vent is part of the door panel. You need to remove the screw in the duct in order to remove the door panel (also called a door card). Once you have the door panel off you'll be able to get a better look at the air vent. I
believe you'll find that it is adhered to the surrounding leather (as opposed to retained with clips, etc). I don't know this for certain as I've not yet removed mine, but I'm pretty sure.
Best of luck with it - let me know what you find out
d-