As best I can tell there's nothing at www.tadpole.com
that addresses the problem at all. I've been in touch with some people from gdc4s (who bought tadpole) and they are trying to find someone who can answer this type of question. They seem to know what they are supposed to--exactly what their documents say at the highest level and nothing much more. They can't explain why Sun's official DVDs won't boot, much less why I can't get a linux kernel to boot. I'm still hoping for something from them, but it's been several days since I last heard anything and I'm pursuing whatever I can think of.
My latest attempt, once I get the download finished, is Debian. I wasn't aware they supported Sparc, so maybe this one will work.