FBXOverride.cs

using UnityEngine;
using System.Collections;
using UnityEditor;
using System;

public class FBXScaleOverride : AssetPostprocessor
{
    int InModelCount;

    void OnPreprocessModel()
    {

        ModelImporter importer = assetImporter as ModelImporter;
        string name = importer.assetPath.ToLower();

        if (name.Substring(name.Length - 4, 4) == ".fbx")
        {
            importer.materialName = ModelImporterMaterialName.BasedOnMaterialName;
            importer.materialSearch = ModelImporterMaterialSearch.Everywhere;
            if (!assetPath.Contains("_ANIM"))
                importer.animationType = ModelImporterAnimationType.Legacy;
        }
    }

    void OnPostprocessModel(GameObject g)
    {
        InModelCount = 0;
        if(!g.name.Contains("_UN"))
            Rename(g.transform, g.name);
    }

    void Rename(Transform transform, string name)
    {
        MeshFilter m = transform.GetComponent<MeshFilter>();
        if (m)
        {
            if(InModelCount == 0)
                m.sharedMesh.name = name;
            else
            {
                string newname = name + "_" + InModelCount;
                m.gameObject.name = newname;
                m.sharedMesh.name = newname;
            }
        }
        InModelCount++;
			// Recurse
			foreach (Transform child in transform)
                Rename(child, name);
    }
}