I think you need JavaScript on your page to react on the mouse over events, and to transmit them to your sketch. Not sure how to do the later, as I haven't played much with PJS.

Thanks for the info! I'm using Indexhibit which makes all of this really funky. I actually can't even figure out how to get the sketch to show up in the first place. I've looked at all of the files I need, as well as the next I need to add into the body of the HTML, although because Indexhibit is a CMS it functions a bit differently which makes things difficult.

Check out the  Writing Processing code with JavaScript in the  http://processingjs.org/learning page, I haven't try this myself but looks possible

Yeah, that's definitely a helpful link and works perfectly for embedding a sketch using HTML. Unfortunately I can't get it to work properly because I'm using Indexhibit which is a little funky for embedding processing.js

I was actually just looking into this problem myself. Here is what I've found.