Using scene color / scene texture in a post process material?

I’m trying to create a post process material that resembles a point cloud (tweaking the chameleon post process grid cell)

Everything works perfectly fine while using a constant 3 vector for the color of the points (cells), but once I try to replace that node with either a SceneColor or SceneTexture:SceneColor node, it throws out an error. I’ve been scouring forums and reddit for some sort of work around but there doesn’t seem to be any. I read that the ability to use SceneColor or SceneTexture:SceneColor was recently removed intentionally for optimization reasons, however since many studios are now using UE4 for film production, so I feel like this should be added back in?

Are there any workarounds that I may not be seeing?

How is the point cloud going to appear? A simple drawing or other example would help in suggesting something.