I added a VMF Exporter to Wall Worm recently. It was available for a while but didn't have accurate UVW coordinates for brush geometry. That problem is solved. You can now export your scenes directly from 3ds Max into Source (with models, displacements, lights, brush geometry, 2d sky, 3d sky). If you own Convexity (and can add Convexity point/brush entities) the exporter will also export those entities ... and I've made an entity I/O for those (this I/O interface is still under development and poorly documented, but you should be able to figure it out until I've documented it).
Here's the video sharing an overview:
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