Dang, remind me to put this in the FAQ.
bagman, in my experience, the steeling process is pretty tolerant of the angle you choose. I try to match the angle that I had sharpened at, but these days I don't try very hard to hold it. Whether or not I let the angle slip, I haven't seen huge difference in the results while steeling -- unlike while sharpening, when the angle has to be held perfectly all the time.
Note, however, that I use a SMOOTH steel that takes off no metal, all it does it re-align the edge. If you're using a grooved or other toothy steel, steel might be removed, and whenever steel is removed it's important to hold the edge constant.