"is it possible?" is always the wrong question ;-) Two basic ways I would think of and both require some work and knowledge on your end:
- Extend the `favoritesClass` in your theme's functions.php or a custom plugin. Then override the original `ad_removeButton()`class method with your own in your child class.
- Use CSS via your theme to add an image in the background of the button which is not a `<button>` but a `<input type="submit">`.