I don't think iMovie'11 have the Text Safe TV boarder function as FinalCut. And in a way when creating DVD menus in iDVD.
But iDVD don't change the Movie to safe boarder - BUT one can in iDVD
• Drop movie into SlideShow project and here change Scaling so that the picture get a black frame and thus shrinks so that all is visibly on a CRT-TV (with overscan - as they all has)
Alt. is to go for FinalCut - where text tools are so much better.
Yours Bengt W