How do I add custom menu support to a thematic-based theme?

I am currently using a theme called organique based on thematic. The problem I am running into is that on the menus screen I get the message:

"Your theme does not natively support menus, but you can use them in sidebars by adding a “Custom Menu” widget on the Widgets screen."

This does allow me to add my menu to the sidebar, but in order to use this theme I have to be able to replace the main menu bar across the top. Is there a way to do this?

I tried adding the custom menu widget to the "Index Top" widget area, but nothing in this widget area seems to show up.

Any help would be greatly appreciated.