I have been playing round with an unordered list that I have used CSS to alter the bullet image from the usual black spot to a ball graphic.
I have used the background-image rather than list-style-iamge as another issue I was getting was that the text of the list was not centred vertically on the bullet symbol and it didn't work either as far as the image toggling goes.
I have played around with the background-position attribute and found that when the mouse hovers over the link the background image appears but only in the section of the li element where the text is, not over the existing sphere image. I then tried making its value negative and as you get nearer to the left edge of the screen it just disappears behind the original image that was layed out in the CSS for the li element.
If you visit this page you will see how it is with a background-position set to -20 so the image is appearing but when I set it to -40 it does not replace the original image.
Lnk to my test page
The Style is in the sheet so if you view the source you should see where I have got to. Any help with this using CSS would be greatfully accepted.