The "ncursesw" (w for wide) supports the extended ASCII set. Dragonfly 3.2 does not support this and I've not yet pursued it enough to get it to work. You could consider extending your engine to do so, but some of the curses calls would need to change. E.g., mvwadd_wch(). However, there can be difficulties in getting the full platform support, too. See:
Once support is in place, you'd have to be creative with making your sprite files since a common editor cannot add nor display the extended set.