Hi Becki
The Shuttle has an SDI input too right? In that case one of BMD's Analog to SDI Mini Converters would seem to do what you want. Here's a link to a blog post from someone using one to feed a KiPro, might be some info in there you can use:
http://teamjaded.com/2011/04/aja-ki-pro ... xh-a1.html
Hope it helps
Andy