replacing checkboxes with images

[eluser]bibiki[/eluser]
Hey there,
could someone guide me on how to replace checkboxes with images. I want users to be able to make their selections based on images they see instead of checking as <input type='checkbox'/> makes possible.

I know I need to use javascript, but do I need to pass that javascript to form_checkbox(), or do I do that referencing some javascript file on top of my html/php file?

thank you in advance.