Assigning Volume shader at render time

I'm trying to modify the 'Standard Example' scripted 3Delight render script to tell 3delight to use the Volume shader from the camera.

When rendering with the standard (not scripted) 3Delight rendering, the volume shader takes effect. In the 'Standard Example' render script it does not. The camera is created via Shader mixer, its Root is a Volume brick.

I suspect the call that is required is Renderer.riAtmosphere(), but I'm unclear what to pass for the parameters. Confusingly, the Camera variable does not have a getShader() method either, which leads me to believe at runtime it is not a dzShaderCamera as I would expect.

Any hints?