Thanks so much for all the replies. My other opton would be to buy a black rooster???
That would be MUCH simpler. If you cross a black rooster with a chocolate hen, ALL the boys will be black split for chocolate. Cross any of them back to the chocolate hen and you should get chocolate offspring of both sex:
25% black pullets
25% chocolate pullets
25% chocolate cockerels
25% black split to chocolate cockerels