First of all, I have been in pain since Friday afternoon, and since I know this affects my mood I try not to post much when this happens (in pretty much any form). Progress on the bustier-done-corset-style Kwik Sew 3850 is slow because of this.
I have figured out a couple little tricks to working with that poly boning stuff you can buy at Hancock or Wal-Mart. First of all, you can iron the stuff flat! Honestly, I don't know why I didn't realize this before. I know it is heat-malleable because wearing it next to the body causes it to conform to the curve - as opposed to holding its shape which is what I originally wanted it to do.
Second, if I pull it out of its casing I can stitch it into place using my boxy-style zipper foot that came with each of my little cheap Brother machines. The poly boning is either exactly or very close to the height of a standard zipper, so it fits perfectly and the foot keeps the needle out of the poly boning. Gratuitous pic for Elaina, who requested "more pics" last night: