I have previously published nine-squares with a diagonal word in the NE-SW (=SW-NE) direction. (Nine-Square with Palindromic Diagonal, May 2002), and with a word in the NW-SE direction (A Nine-square with a Non-palindromic Diagonal, November 2002). The square below completes the set, having a word as the SE-NW diagonal.
"A Nine-Square With The Remaining Diagonal,"
Word Ways: Vol. 36
, Article 12.
Available at: http://digitalcommons.butler.edu/wordways/vol36/iss2/12