Hold the hinge against the door frame in the desired position with the hinge aspect, which is the metal rod joining the two halves of the hinge, pressed against the exterior edge of the door. Mark the position of the hinge on the door frame, using a pencil.
Repeat Step 1 for the next and any subsequent hinges.
Hold a level vertically against the vertical edge of the marks you made previously for the top hinge. Position the level so the edge is straight up and down. Trace the edge of the level with a pencil to correct the position of the edge of the hinge mark.
Tape a weighted string, which simply has something heavy tied to the base, above the mark you made in Step 3 so the string follows the path of the line but does not touch the ground. Trace the position of the line so you have an accurate position for the edge of the remaining hinges.
Check the level of the mark you made in Step 4 for each additional hinge to verify the marks are accurately leveled from top to bottom while following the vertical line.
Press the end of the chisel against the marks you made for the location of each hinge so the beveled edge of the chisel points toward the center of the marks. Hammer the chisel straight into the wood along the marks, creating a scored outline of the hinge.
Hold the hinge against the scored outline to verify the dimensions are accurate. You should be able to see the scored outline around the edges of the hinge.
Press the point of the chisel into the external edge of the door frame so the flat edge will cut straight into the frame, creating the actual inset cut. Position the chisel so the cut will be deep enough for the hinge to sit flush with the surrounding frame and the upper edge of the chisel is flush with the upper mark.
Hammer the chisel lightly until the end comes to the vertical mark, which will allow the layer of wood to pop off cleanly. Repeat down the height of each set of marks you made until the inset is fully carved out.
Press the hinge into the inset cut to verify the depth. Repeat the process until the depth is accurate.