在iPhone上自定义UITabBarItem图像/标题

I'd like to add a custom title to one of the predefined UITabBarItems. Whenever I select the particular instance I like in Interface Builder -- if I modify the the title it gets preset back to a 'custom' identifier. Ideally I'd like the book icon from the 'Bookmarks' identifier with my own custom title.I'd like to add a custom title to one of the pr