I use laser-printed patterns all the time for metal work. Just print on paper, cut to approximate size, then use an artist spray adhesive (non-water based). Spray a light coat, stick it to the metal and machine away. If you are going to use coolant, you need to scribe through the paper, as the adhesive will be loosened. I suspect you might have the same problem with toner transfer.
My laser printer is not very accurate (+/- 0.004 per inch or so), but it works for approximate work. You may have to fit critical dimensions. The LJ4101 stretches in the lengthwise direction. An older LJ4 is actually better in that regard.
An additional variable is the paper itself, which can change size quite a bit. I am looking at higher grade rag and synthetic papers to see if I can get the variation down.
John