Average Normals is a Maxscript that averages all the vertex normals for each selected faces, so they all point the same direction.
To use the script, you have to select all faces on which you want to flatten the normals and run the script
You have to select faces coplanar, and have chamfer edge between two coplanar area.
Like the gif above
3ds Max9 +
The Script is in zoffty_Tools Category, Average Normals