Changing the footer mid-document

Hi

I have a document which, starting at about page 5, has some graphics in it. What I'd like to do is to either (a) change the regular footer, or (b) add an extra footer, to say something like "These are internal graphics", starting on the first page where the graphics show up.

I cannot figure out how to do this in acrobat professional 7.0. Can anyone point me in the right direction?

Thanks,
T. Terry