I have used this on Entities and Huds, but I don't think on any Segments yet.
It should, but I don't know, partly because I don't use photoshop either.
All I have is the MS-Paint that came with Windows.
When I make a JPG Texture with RGB 0,0,0 it comes out transparent.
It works for my Entities and Huds. That's all I know.
Try it with Photoshop and let us know if it worked.
Edit
I used this on a Wall Section I think, but it was an entity like the false wall and not a Segment.
If memory serves.
Speaking of Invisibility,
I never finished that script I was working on to make the player invisible.
That one was starting to wig me out, and I'm beginning to think it will never work right.
Sorry DQ, but it looks grim. So, I have to put that one on hold for awhile.
I am going to work on this spaceship thing to refresh my mind.