Have you heard of Vecco? Vecco is a spray paint and stencil type of product that you can use to decorate your rug! Apparently, if you mess up, which I am very likely to do considering how clumsy I can be, you can just vacuum up the product. It won't stay unless you spray on the protective sealant as well.
I would be interested in doing this in a medallion pattern. I think the fleur de lis stencil comes pretty close.