Pass cube map to metal shader in RealityKit 2

I would like to pass in a cube map to a custom material shader in RealityKit 2 so I can achieve effects like custom reflections and iridescence.

I am aware of material.custom.texture and material.custom.value as talked about here: https://developer.apple.com/forums/thread/682632

But those only allow for a 2D texture and a                     simd_float4 (a vector of 4 float values).

And I am aware of how to pass in animatable custom parameters as talked about here: https://developer.apple.com/forums/thread/682632

But I would like to be able to sample a cube map instead of a 2D texture. Any help is much appreciated.