I used the MX mode which has 8 different frequencies around 2500 Hz so it is quite different from regular zappers. There are Rife frequencies that are specific to Basal cell so those might be a good choice. A 2 x 3 inch copper pad might work but as you stated, it is a difficult area to keep a constant contact. IMHO, any zapper is better than no zapper, but seek out the best that you can find. You need fast complete action because Basal Cell can spread.