change checked/unchecked checkboxes image

Hello,

I was wondering if someone could help me in changing (theming?) the icon (image?) of the checkboxes for checked/unchecked.

I dont want to change the style of the checkboxes on the whole site but just target a specific cck field (type: text with widget: checkboxes). I would like an image to be shown for checked and a different image for unchecked.

I would appreciate any pointers!