It bothered me that I couldn't lay my hand on an article dealing with
this so I went on what I figured might turn out to be a snipe hunt.
Found a snipe, though.
Ian Kirby did a sidebar on sharpening backsaws (including dovetail
saws) in issue #39 of FWW, which was later compiled into the Taunton,
"Fine Woodworking On...", series book, "Hand Tools.
It looks pretty solid. If you don't have access to either of the
above sources, I can scan it and send you a .jpg.
Thomas J. Watson-Cabinetmaker
Gulph Mills, Pennsylvania