Measure your yarn so it's 5x your desired (finished) cord length.
Add one beater to your mixer. Loop one end of your yarn through. Tie yarn ends together in a knot (Julie used a slip knot) so you have one large loop running through the mixer.
Hold the knot in your hand and step away from the mixer until you have a taut tension. Then, have your partner start the mixer on the low setting. Once it gets twisted enough that the yarn is tight enough to "jump" have your partner turn the mixer off.
Place your finger at the halfway point - guesstimating is fine. Hold the ends together and let go. It will totally twist up on itself, smooth it out with your fingers until it becomes a four-ply cord with neutral tension.
You can untie your tie or slip knot, then you'll need to snip the other end off of the mixer. Cut all ends flush with each other and tie them in a knot. Voila, you've done it! Now...who's ready to make another?