Switch bone with external resource?

Hi there,
As AS3 version, we can switch bones with any texture we want, 
But with Unity, maybe that's feature is missing,

<code>
        Bone img = armature.GetBone ("step1_01");

```
    img.Display = Resources.Load("1/texture", typeof(Sprite));
```

</code>

Is there anyway for us to accomplish this?
