I don't think there's a way to do what you want. Maybe you could manually figure out how big each tool tip box should be. Then ... (let's assume you have a function that creates a tool tip with a given text) you would have to pass the desired size as a parameter too.
Maybe just create a status bar. You could put a very long text box across the bottom of the screen. Then you could have the tool tip text go to the status bar.
I know this isn't exactly what you wanted, but it may be the next best (doable) thing.