I have 2 frames in one page like this (home.html)
You could grab the Frame and div you are wanting to manipulate and pass it into a variable.
var statusText = top.frames["treeStatus"].document.getElementById('statusText');
Then you can do anything you want to it through jQuery.
$(statusText).whatever();
Though sometimes you just can't get around having to use frames, keep in mind that the tag is obsoleted in HTML5. If you ever plan on moving up to HTML5, you'll have to use iFrames.