Composure - Access custom stencil (or other buffer) in transform pass

Hello,

Using 4.22 I am trying to use the Composure plugin to mux together a live video stream with a hairstyle. One issue I have is culling the mesh faces that are behind the face.

One approach is to use a custom depth stencil and use that as a mask, but we do not have access to the stencil in opaque materials.

I was hoping to use a TransformPass with a custom material to utilise the stencil, however, it seems no buffers are available in the Transform Pass materials.

I have confirmed that the stencils are being rendered by exporting the comp using sequencer, and using the buffer visualisation in editor.

Instead I am having to include a face mesh with an unlit green material, and use a ChromaKey pass to mask those pixels:

Is there any way to make the buffers available to a TransformPass to achieve this without needing a chroma-key transform pass?