mxk,
That's exactly what I was looking for! Thanks for the tip.
Since not all of my limit switches are installed, I omit (comment out) the "G28; home all axes" line and a "M108". I didn't find a "M109" command.
Also, I found I needed to change the "printer center" coordinates in slic3r from 100,100 to 50,50 to fit the smaller Quantum print bed. This is probably not news to many of you, but it was to me. I was wondering why it was chugging away in just one corner of the print bed. Now it's properly centered.
I'm printing out an imaginary Pikachu right now:
http://www.thingiverse.com/thing:22012Fabulous! Thanks again, everyone.
Dale