Transparency in VR

I’m trying to build & run a simple VR project such that Alpha = 1 for some pixels of the render target’s texture.
I want to do that in order to do custom AR tricks with this texture in my VR plugin.

So far I’ve been trying to modify Skyboxes material to be translucent, but that hasn’t worked.
Is there a good way to do it?

Did I do a good job of describing what I want? Basically, I want pixels that represent sky to be RGBA 1,1,1,1 after a frame is rendered.

This sounds a lot like the DitherTemporalAA node (alpha treshold controls the transparency), just plug it in the opacity input. You dont even need the tranclucent material, masked is enough. There is one problem tho, TemporalAA doesnt like it a lot, but just test it and you will see if it suits your needs.