Auf der Suche nach einem 3Ds Max zu Hammer VMF Exporter bin ich hierauf gestoßen (wen es interessiert):

The Wall Worm Displacement Tool is a MaxScript that allows you to create displacement terrains for the Source Game Engine inside 3ds Max 2008+ . (It may work in older versions of 3ds Max with AVG installed.)
Key Features

Build terrain inside 3ds Max
Use standard 3ds Max design tools and modifiers to sculpt terrain
Sew displacements that do not line up
Paint blend texture alpha inside Max
Exports terrain into a VMF file (with the sky texture if a Sky Writer Helper is in the scene)
Works with Sky Writer
Works with Wall Worm Model Tools

WallWorm Displacement Tool

ich mag sub kulturen