On the mainland it's accessible from the drivers side, guess on the islands it will be on the passengerside ^_^ .
1) First remove the "Philipsscrew" holding the panel at the side of the middle console. You can turn it a few threads out and then pull the whole screw/clip out. Now remove the panel, the only thing holding it in place are 2 clips opposite the screw so just pull.
(Sorry, no pics :( )
2) If you have a LHD car then you now first have to remove you're throttle pedal. If you have a RHD car you can skip this step, assuming it's on the passengers side.
Pedal is mounted with three 10 mm nuts. Remove the nuts, pull the pedal towards you and unplug the plug.
3) Now you see a cover which is hold done by 4 screws with Torx heads. Remove all 4 screws.
4) Remove the cover, it will just come of or even fall off.
5) You now see the side of the filter, just pull it out. Now look/feel if the bottom of the slot is clean, no branches/leafs/etc.
6) Take you're new filter and look at the top to see if the arrows point in the direction of the gearshifter. Now slide the new filter in.
7) Put the cover back and put the 4 Torx screws back in and tighten them. Only gently, it's just plastic there in!
8) Click the side panel back in and just push the "Philipsscrew" clip back in.
9) Put back the throttle pedal bij fastening the three 10 mm nuts and reattaching the plug.
10) You're done, don't know what the replace interval is of the cabin filter but you should be good for a long time :)
The filter that i removed was about half the thickness of the after market one i put in. The slot is the same thickness as the after market filter so i don't know why the original one was just half the thickness. Ford moves in mysterious ways ;)