The Diary is quoted in a couple of books I know of...This Astounding Close...and Last Stand in the Carolinas: The Battle of Bentonville. Both books are by Mark L. Bradley
The following web site http://www.tngenweb.org/bradley/BradleyPubs.htm list's the diary, so the only thing I can tell you is to contact the Library, and see what they can do. The copy I have was sent to me by a relative, don't know where she got it.
William E. Sloan was in thru nearly the whole war, finishing in North Carolina. He was a cousin to my GGGrandmother, Minerva Ann(Sloan)Thornton
Respectfully:
Kevin Dally