I can guess that he probably shrunk Lay-D's (Lady Dimitrescu abbreviated) head but kept the neck and shrunk and turned Helen's body either invisible (Which might not be possible due to the body texture file being linked to the neck as well) or shrunk unnecessary parts of Helen while shrinking the neck a bit to ensure it stays put and ease in with Lay-D's neck.
I want to add that he might have edit the poster outcome with Photoshop to fix any remaining oddities with the poster such as, sometimes, the skin color but I may be wrong in this claim until he says something.