To add materials override you need to right click on animation set and select "Add override materials". This will allow you to see "materials" folder if you open this model in Element Viewer. There you will be able to open any material and add some custom attributes that will override corresponding parameter in this model VMT file.
List of attributes that could be overridden (or added) in SFM:
- $basetexture (<String>) – VTF path for texture replacement;
- $phong (<Float>) – brightness of phong effect;
- $color (<Color>) – changes color of the material.
List of attributes that cannot be overridden (or added) in SFM: WIP