Brian Pape , Sep 18, 2007; 04:04 p.m.
There is, of course, no such thing as a "macro mode" on a Rebel XT (or any DSLR that I'm aware of, for that matter). The discussion you referenced seems to be the blind leading the blind.
If you want a macro shot, you'll have to have a macro lens, extension tubes on an appropriate lens, a reverse mounted lens, etc. You are simply bound by the parameters you can control which affect the size of the image on your sensor (which is the lens), how close that lens can focus, and the aperture you choose, within limits of what the lens supports.