OnKeyUp in 2.0 RC1

Can anybody give me some tips for binding an OnKeyUp event to FCKEditor 2.0 RC1?

I have a div on my site with very limited space for content, so when users edit this, a pop-up window appears with the editor on the left and a preview of the div on the right. As they type in the editor I need the data to be updated in the div with something like:

document.getElementById('preview_div').innerHTML = document.getElementById('FCKEditor_instance').innerHTML

I can't figure out how to get any events to fire with key presses though.

Thanks!!