Soft Selection to Vertex Colors is a script for 3ds Max, created by Jon Seagull, that turns a soft selection into painted vertex colors. Working on Mesh or Poly objects, it converts the selection into grayscale vertex color values stored directly on the geometry.
The script provides four modes: replace, add, darken, and subtract selection. Each sets how a soft selection is applied against the vertex colors already on the object, so you can control how each pass combines across separate operations.
Jon Seagull works as a consultant and technical director on clients' internal 3D pipelines, covering technical direction for large or unusual projects, custom tool creation and scripting, and emergency troubleshooting. This script is one of those tools. It is listed at version 0.4, a demo video is available, and further links sit on the developer's page at jonseagull.com.