However, you then still have the problem that you're loading the overLIB script(s) for users who don't need it. I think the best way to avoid this depends on the rest of your stack.
Another thing to think about is the purpose of the hover tips. If they are useful on your desktop site for helping users to learn about where they're going without making the investment of a click, why aren't they useful on your touch device site? I know that hover is clunky on touch devices, but I think they're common enough since there's no alternative yet. I'd bet that touch device users understand the flow. The only example that comes to mind is Seamless.com - when you select a menu item from a restaurant, you get a "hover" description and then it requires a second click to select the item.
I realize that this is an old question - answering for the Googlers. :)