Further to what Gene said about using Magic Markers, make sure the surface is really clean first or the magic marker will "float off" during the etch. You may want to get some latex gloves from a paint store so you don't get finger prints on the steel. Go to the store and get a selection of different brands of permanent markers. Some put more ink on than others. You want a good thick coating. Obviously, ones with fat tips will cover large areas much faster than the fine tipped ones. We did not notice any difference between the different colors. If you need to recoat some part, wait a few minutes or your first coat comes right back off. After etching, almost any solvent (alcohol, acetone etc.) can be used to remove the resist. Alternatively, a Scotchpad or steel wool followed by a rinse in water would work but may mess up the pattern on your steel. We used this method to etch copper off our circuit boards in school.
Phil