I am fortunate to own a copy of the book about William Madison Wall by Garth D. Mecham. It was published in about 1960, I believe, (no publication date is found in my copy). I got my copy from Pioneer Books, owned by Mr. Horsely in Provo about 20 years ago. At that time he had just the copy I purchased, but I believe had access to some photocopies of the book as well. How to get one today? Short of photocopying someone's copy, I don't know. The descendants of Wilford Woodruff Wall continue to have a Family Reunion, generally in the Salt Lake City -- Heber City region in the mid to last part of August. One of them may have a copy or access to one.
That's about as much as I know. I hope it helps someone.