voner: for the motor cortex position, we use the "C3" position on the top of the head between the ears, but as my wife's worst pain is below the waist and near the midline of her body, I keep the electrode close to the midline of her skull rather than more lateral, closer to the ear. If you check out a homunculus image online, you'll see where the different parts of the body correspond to the motor cortex (I've taught Anatomy and Physiology for many years, so I knew the homunculus would be informative). But bear in mind that the precise position isn't real important given the wide distribution of the electrical charge.

Many people use special elastic bands to secure the electrodes, but we use self-adhering ace wrap, which you can readily find at a drug store. We first secure the cathode (black) lead in the supra-orbital position on her left forehead with about a 20" strip of ace wrap. We then secure the anode (red) lead to the motor cortex using a similar stip of ace wrap. The ace wrap works perfectly fine.