This request was made this morning. Unfortunately it's rainy and colder outside - cold enough that we might get snow overnight into Saturday. That eliminates the way I'd like to approach things: slap on some panties and go outside w/ a potty at the ready. Then when she has a few accidents and gets a feel for it - bam, progress.
At least if we're not allowed to go out and live our lives there won't be the obstacle of public restrooms anytime soon.