LuxMax is the 3ds Max to Luxrender exporter. Its mostly made using maxscript. At the moment despite the fact that is under development and not a finished project, it supports all lighting and render settings, all Luxrender materials/image textures and even most of the blender and Luxrender procedural ones. You can also preview your materials without exporting your scene, use the new Luxrender 0.8 interior and exterior mediums as well as environment hdri lighting, 3ds Max native standard lights and specific Luxrender ones.
Recently LuxMax started also support for SLG in the same exporter pack which though in early development is stable enough to use many of its features.
You can grab LuxMax latest release from the repository where all latest changes are commited: http://src.luxrender.net/luxmax/
In order to make LuxMax better we highly encourage you to try it and report your suggestions/issues in the development thread.