I took the amber inserts out of my corner lamps on my pathfinder a few years ago after reading this thread.
Should be the same process for your headlights.
It sounds easy, but you really need to be careful and take your time.
I used a heat gun to soften up the sealant, but I went at it very slowly so as not to melt the plastic housing.
You also need to re-heat the sealant when putting it back together so that it seals properly.
I also put an extra (small) bead of silicone around the edge to make sure there are no leaks.
The last thing you want is to have water vapour in the lamps.
Good luck.