I do remember something like that.I think I have it. It's called Spirits something, I think. It had MATs for the unimesh figures and for several popular hair and clothing items. You could make figures transparent, in whole or in part.

The bad news is old scripts don't run in Poser 12. It uses a different version of Python. It was unavoidable; Python 2 reached its end of life, so they had to switch Poser to Python 3. 

So even if you found the script...it wouldn't work in Poser 12. 

There's a product in the store that does something like that.

https://www.renderosity.com/rr/mod/bcs/?ViewProduct=98608

But it uses Semidieu's Advanced Shaders script. Once a freebie at RDNA, no longer available now. And it wouldn't run in Poser 12 anyway.