iBook widget hack

Is it possible to alter the look of the call-outs in the interactive image widget? I'm thinking specifically of changing the current text box and line/pointer to look like a speech bubble in a comic. I know that I can do it in an html5 editor like Hype, but I want to use it over and over and really like the convenience of just dropping the images and text into the widget rather than creating an html5 widget for every frame.