The javascript is the really easy part - the hardest part is getting the items you want out of the normal edit/new post/thread area and into a seperate div container.
For example, this structure makes it easy:
Code:
<div id="post_options">
<div>
<!-- A table goes here -->
<!-- Another table goes here -->
</div>
</div>
Once you've got the HTML right, then all that's left to do is include scriptaculous and do a lovely slide effect. Just have a blast creating some new MyBB tables in the templates, move the things you want into the structure above and I'll write up a quick script.