Only thing I can think of is rinsing in a bowl (like a soup bowl) with the ribbon hanging over the side. But you would still get some of the ribbon stiff.
I'm not quite sure how you'd do this. It seems to me that if you are using a washaway stabilizer, it would migrate into the ribbon when you washed it out. Probably you'd need to experiment a little to get it exactly as you'd like it. I'll be interested in seeing what you come up with.
I too, have not heard of this.... I'll be looking for your answers!!