I did a frame-mount in a Ladies, BUT I built a 24" vintage cruiser for my wife, and she rides a 24" Whizzer, both boy's models, and she's only about 5'6".
I don't have a pic of her bike in this computer, but it is in the bottom of my gallery.
http://www.simpsonmotorbikes.com/Dianes%20bikeTN.html