Mom broke her arm and refuses to shower. How do I get her to bathe?

OK, quick question. My mom broke her arm nearly two weeks ago (it took nearly a week to get her to see the doc.) Now, it's been a week since she had it set in a cast. She can't get it wet. Best way seems to be to wrap it in plastic and tape it off so it can't get wet.
Well, it's been a week and she refuses to shower. I have offered to help her, either by sealing off the cast or helping her bathe. Nope. Whatever idea I have she shoots down and says she simply won't bathe for the four to six weeks. (She already says the doctor will have to remove it after four weeks, and that is that.)
My mom doesn't like to take a daily shower, which is fine, but she is diabetic, smokes, takes lots of pills, drinks very little water and likes to wear polyester house dresses all the time. In short, it's a recipe for smelling very bad.
Anyone have any advice for getting her to clean up? We got her a shower seat so she could sit and not lose her balance but she won't use it. No one can help her bathe apparently. I get that, as I wouldn't want someone washing me down either if I could help it, but man is she going to stink!