Hmm... I think I know how to do this, but it isn't a code hack, and is IE specific. Hmm...I can't find my source. Try this:
in your postbit template, put this before the part you want to scroll:
Code:
<div style="overflow:auto;height:500;">
and this after:
You can change the height number. Be aware, however, that this will make it take up the specified height even if it is smaller.