Unity wizard to change sorting layer and order for one or several objects. Here http://youtu.be/lIx9j5o8uEQ you can find screencast how to use it

SetRendererLayerWizard.cs

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


public class SetRendererLayerWizard : ScriptableWizard {
	public Renderer     renderer;
	public Renderer[]   rendererList;
	public SortingLayer sortingLayer;
	public int     	    sortingOrder     = 2;

	[MenuItem ("GameObject/Set Renderer SortingLayer")]
	static void CreateWizard () {
		ScriptableWizard.DisplayWizard<SetRendererLayerWizard>("Create Light", "Update");
	}


	void OnWizardUpdate() {
		if(renderer == null && (rendererList == null || rendererList.Length == 0)) {
			helpString = "";
			errorString = "Select gameObject with renderer on it \n or drag couple of these objects in to the rendererList";
			isValid = false;
		} else { 
			if (renderer != null)
				helpString = "Current sortingLayerName = " + renderer.sortingLayerID+ "\n" +						
								"sortingOrder =" + renderer.sortingOrder;
			errorString = "";
			isValid = true;
		}
	}

	void OnWizardCreate() {
		if (renderer!=null)
			updateRenderer(renderer, sortingOrder, sortingLayer.id);
		if (rendererList != null && rendererList.Length >0)
			foreach(Renderer r in rendererList)
				updateRenderer(r,sortingOrder, sortingLayer.id);
	}

	void updateRenderer(Renderer renderer, int sortingOrder, int layerId){
		renderer.sortingOrder = sortingOrder;
		renderer.gameObject.layer = layerId;
		EditorUtility.SetDirty(renderer);
	}
}

[Serializable]
public class SortingLayer{
	public int id;
}

[CustomPropertyDrawer(typeof(SortingLayer))]
public class SortingLayerIdPropDrawer:PropertyDrawer{

	public override void OnGUI (Rect position, SerializedProperty property, GUIContent label)
	{
		EditorGUI.BeginProperty(position,label,property);

		float offset = 4.0f;
		position.x+=offset;
		position.width -=offset * 2;

		int origId = property.FindPropertyRelative("id").intValue;
		string origString = LayerMask.LayerToName(origId);
		int selectionId=0;
		List<String> layerNames = new List<string>();
		for (int i = 0; i < 32; i++)
		{
			string layerName = LayerMask.LayerToName(i);
			if (layerName != string.Empty){
				layerNames.Add(layerName);
				if (layerName.Equals(origString))
					selectionId = layerNames.Count - 1;				
			}
		}
		Rect labelRect = position;
		labelRect.width = EditorGUIUtility.labelWidth;
		position.x     += EditorGUIUtility.labelWidth;
		position.width -= EditorGUIUtility.labelWidth;

		EditorGUI.indentLevel = 0;

		EditorGUI.LabelField(labelRect, label);
		int newId = EditorGUI.Popup(position, selectionId, layerNames.ToArray());
		if (newId != selectionId){
			int newLayerId = LayerMask.NameToLayer(layerNames[newId]);
			property.FindPropertyRelative("id").intValue = newLayerId;
		}
		EditorGUI.EndProperty();
	}

	public override float GetPropertyHeight (SerializedProperty property, GUIContent label)
	{
		return EditorGUIUtility.singleLineHeight;
	}
}