Its quite simple to do, especially with a strap wrench - which now lives in my camera box. Those Zen instructions are super clear.
I've removed and left out the locking Screw on mine (it isn't going to fall out, if you have twisted it into position) and I've white painted on the outside an alignment marker, showing the port and housing are in correct position - just so I can quickly check before hitting the water.
I'm changing the ports regularly and having to unscrew the lock got annoying!
I would say the Zen Ports are a little stiffer than the Olympus ports, with the olympus ports sliding in and out quite easily compared to the Zen ones.
(I have both the 9-18mm and the 8mm ports)