This is what I ended up doing in a child theme because I just don't know how to write this in php for the functions file:
<div id="header">
<?php thematic_header() ?>
<div id="tweettweet">
<?php aktt_sidebar_tweets(); ?>
</div>
</div><!-- #header-->
In the docs, there is a list of hooks, but I didn't find many further instructions, or examples that I could really base this off of. You can see it (for a couple days anyway) at http://desperatelyseekingwp.com/test
Thanks for the help!