Add this function in a subclass to get a notification just before a model (.fbx, .mb file etc.) is being imported.
This lets you control the import settings trough code.
// Disable generation of materials if the file contains
// the @ sign marking it as an animation.
class DisableMaterialGeneration extends AssetPostprocessor {
function OnPreprocessModel () {
if (assetPath.Contains("@")) {
var modelImporter : ModelImporter = assetImporter;
modelImporter.generateMaterials = 0;
}
}
}