Can this not be done with facet SOP using unique points? Or am I misunderstanding the question. Probably could arrive a similar solution with facet POP. I made a quick custom glsl for manipulating vertexes in POPs lemme see if I can find it
Edit:
Does this help?
Edit 2 :
Actually This is gonna be broken actually bcus of the changes to glsl naming. Check out this post to update those