I knew I shouldn't have dropped Japanese in high school.
I'm on the Summer Sonic 2012 website. Looks like she'll take the Ocean stage in Osaka on the 18th and the Marine stage in Tokyo on the 19th. No live streaming links have made themselves apparent to me.
Gonna go stalk the Rihanna thread and see if they're faring any better.

Because it looks like the only thing separating Rihanna and Ke$ha at this festival is Jamiroquai. Same dates, same stages, just minutes apart, etc. So if her fans find a way to stream this, it'll work for us too.