Measure the length and width of the cabinet side on which you are installing adjustable shelf pins with a tape measure. Transfer the measurement to a sheet of pegboard. Cut the pegboard to size with a handsaw.
Mark the cabinet side 1 inch from the rear of the cabinet with a pencil. Make a mark at the top and bottom of the cabinet side. Place a straightedge at the two marks and draw a light line with a pencil. The first line of peg holes for the shelf pins start at this line.
Set the pegboard onto the cabinet side. Line up the last line of holes on the pegboard over the line you drew. The line should be at the center of the last row of holes. Clamp the pegboard into place with wood clamps.
Insert a 1/4-inch brad point bit into your drill. Wrap duct tape around the bit to mark the depth you want to drill. Remember to add the thickness of the pegboard to your drilling depth. For example, if you want to drill a 1/8-inch deep hole in the cabinet for the shelf pin and have a 1/8-inch thick pegboard, place the tape around the bit so the last 1/4 inch of the bit tip is visible.
Drill the holes into the cabinet side using the holes in the pegboard as a guide. Drill the hole until the edge of the tape meets the surface of the pegboard. Repeat the process for the opposite side of the cabinet.