If the camera and actor are not moving you could do it with a simple mask using a stone paint job on the actor in photoshop.
You can roto the actor and overlay a stone texture (animated preferably). The stone texture would need to be "crawling" the entire shot because you wouldnt be able to lock it into place on the actor. The actor will "slide" under the texture.
The "pro" option would be to replace the actor with a 3D model.... but I dont think that fits your question.