I have considerable experience with punishment enemas as I am a masochist and they are another way to suffer. They usually involve the use of a double bardex retention nozzle which prevents you from expelling the enema. If you are ever in NYC I highly recommend Mistress Natalie who is extremely skilled in administering them.

I have not tried to combine it with ballbusting but sometimes I combine it with another form of CBT I dreamt up.

Here is a review of a rather unusual session I did with her. It might pique your interest.

http://domina.ms/~domroot/thebuzz/ubbthreads.php?ubb=showflat&Number=3510#Post3510