How to replace text links with icon links in WP 3 navigation menus

The new WordPress 3 navigation menus are an excellent tool to design your own menus, mixing pages, categories and custom links. iThemes created video tutorials on how to use the new WordPress navigation in Builder and Flexx theme. The following tutorial will show how you can replace the text links in the navigation menu with images. It can be used for any theme, on any WordPress site running WordPress 3+, but it is based on iThemes Flexx.