The San Cha points are Sanchayi (A02 or 22.15), Sanchaer (A03 or 22.16), and Sanchasan (A04 or 22.17). They are sometimes collectively referred to as Sanchasan A01-A03. I was confused by the naming when I first encountered these points (and frankly, I think the people who taught them were too), so it helps to know that yi is Chinese for one, er is Chinese for two, san is Chinese for three. . . hence the naming.
These aren't hard to locate. Sanchasan 22.17 is located much like San Jiao 3, about 1/2 cun proximal to the web margin between the 5th and 4th MCP joints. To find any of these points:
Have your patient make a light fist as shown below.
Palpate to find the hollow spot about 1/2 cun proximal to the web margins.
Slide the needle in just below the skin and imagine threading it in like you are trying to reach Heart 8, but you don't have to go that deep. I use 1 to 1.5 cun needles and thread them in about 3/4 of the way.