How to add more vulgar fractions to glyphs?

Is there a way to convert a fraction into a single character vulgar fraction? We use Minion Pro and Myriad Pro, but all I can find is nine common vulgar fractions. We need more. When we export xml from Indesign CS3, the vulgar fractions look good on our website, without needing anything done to them using CSS. Is there a way to build or buy a more complete set that included 13/16, 15/16, etc.

Thanks