First of all you need to take off the weather seal, just a few plug type clips and three hidden screws.
Then that will reveal the metal strip behind it which helps hold the weather seal in place. This is held on by three screws and double sided tape.
Carefully peal that off.
Now this is the tricky part. There are three clips holding the trim on. One at the bottom, middle and top. Ofcause if all these clips went the same way there is a high risk of it falling off. So they (Nissan) made the bottom and middle clip the same but the top clip is the opposite. Bottom and Middle slide downwards off the clip and Top one slides up off the clip.
So the easiest way to do this is to lever the top clip out. They use a 'bee sting' type of clip. If your clever enough *like me * You'll find you'll be able to put some outwards force on it, lever the top stinger down and it will pop out then do the same with the bottom one and the 'bee sting' is now out.
There... that's the hard part done.
Now holding the trim flat as possible (ie. in the closest position as possible as it is when on the car) hold the bottom part with one hand and other hand still holding the top part out enough that the clip doesn't go back in push downwards.
Now with a bit of force the trim will all of a sudden clip off.
Then you can easily take out the remaining two clips.
Once you've done that side the other will be easy!
Hope this helps. I know these trims are getting rarer so that is why i felt the need to finally give away the secret.
I WILL be having some of these made up in the near future so that there is no more need to pay the rediculas price Ni$$an are charging for them. $300+ A SIDE.
Note: The proper way to get these off (which usually yeilds in a broken one). Is to push the trim downwards, the middle clip will slide off. Then slide it upwards, the top clip will slide off. Then downwards again and it will come off the bottom clip.
All that without the need to take off the weather seal etc etc.
But as i said... usaully ends up with a broken one if you haven't done it before!
Just an addition to the above post. When putting them back on, it is a good idea to stuff the gap behind the beesting clip with some cardboard or silicon or something. As they are the parts that are prone to breaking.
Especially when your trying to push them back in!