Don, from the information you've given I can't find anything more about the poem but there is a fictional account of the incident by an author called James Davenport titled "The Murders at Bill's O'Jack's: A Fictional Account of the Murders at the Moorcock Inn, Saddleworth, in 1832" which was published in 1985.

The Saddleworth Historical Society has a List of publications which include a guide to 'The Bill o' Jack's Murder Trail'.