How to customize header in Blogs MU

Howdy WPMU Dev,

I'm setting up a new MU site using Blogs MU as my main theme. The layout looks good and the features seem like they'll work well.

I can't figure out how to do all the customizations though. When I look through the Customize option, there's nothing to change the logo that I can find. And when I open Theme Options, none of the tabs work. This leaves me with the Blogs MU logo and a wide open field that I can't figure out how to access.

What am I missing?
Support access is already granted, in case you need to take a peek.