On the 2000-2003's for sure they are just pressure tabs. They are plastic with teeth and just use pressure to stay in place. So you grab a hold of the bottom corner and pull firmly. will pop right off. Don't jerk it,,,,,,,just use good solid steady pressure. Its the same for all the attachments in the cushion. I am not sure where you can get them (dealer or auto parts store would be a great start)but if you if needed to put a new one on I am sure you will have to unstitch/unstaple the seat skin to get to the tab and remove it to intsert a new one. I am sure this could be very easily done as you would just unstaple a small section around the tab you need to replace.
The side armrests in the bow have nuts. However in order to fully remove the armrests you also have to remove the center portion because there is one nut on that bow armrest that is directly in the corner next to the center cushion. I know from experience.
(Message edited by xstarrider on October 17, 2009)