Any conversion will not be exact and you will need to edit the materials.
Try to make an exact conversion is a nonsense and useless. If you want that a scene look the same render it in its native application and don't waste time exporting and converting to foreign renderers.
Each rendering engine has its own features and personal implementation of the materials and illumination model, this is the reason why you want to use an external rendering engine: to have something that cannot be done or look better than in the native engine.
If you are able to translate in an exact way a complex Poser's shader tree and scene settings and then export to LuxRender and your conversion is perfect then you will have a Poser's render and not a LuxRender's render and you wasted your time.
If you want LuxRender' to render your scene you use LuxRender features, if you want PovRay to render you use PovRay's features and if you want Poser's shader trees you render with Poser.
You only need to translate the geometry, textures if needed and basic properties of materials (ambient, diffuse, specular, emisive, transparent, etc) and then you must setup the lights that behave in a different way and the materials that also do.

Stupidity also evolves!