Replace a theme hook with a module function(hook)

I have a module that modifies the way menus are formatted for a specific type of menu. So I want the hook_menu_item_link to call picturemenu_menu_item_link, where picturemenu is the name of my module not my theme.

My temp workaround is to call from my mytheme_menu_item_link to picturemenu_menu_item_link, but to make it a contribution worth module I think it should be able to register its function.