I can do this for you within a day. I've ran a few tests and I believe I have figured out how to do it. I can set it up so it will be a separate page that you can upload to your site and then include the page with an iframe on your main page so it will just show your follow button. Users will need to be logged in to ustream, in order for the follow to actually work. I can set it up so if they aren't logged in, they are directed to ustream in a new tab or window so they can log in.
Thanks for considering me.
-Leo