Position the hinge leafs on the door edge, where you intend to install them.
Install a driver bit into a power drill. Install screws into the hinge leafs, to mark the locations of the screws, using the power drill.
Draw lines to mark the outside edges of the hinge leaf positions on the door edge with a utility knife.
Put the power drill in reverse, and extract the screws from the hinge leafs and remove the hinge leafs from the door.
Position the edge of a wood chisel, with the beveled edge down, on the hinge outline. Hold the chisel at about a 45-degree angle, and gently tap the end of the chisel with a hammer, so that the tip of the chisel blade carves out a series of shallow cuts in the door edge.
Stop carving the mortise and position the hinge in the mortise frequently, to make sure that you aren't removing more wood than is necessary. Continue carving out the mortise and checking your progress with the hinge, until it is deep enough that the hinge rests flush with the door surface.
Position the hinge leafs in the mortises, and install the screws into them with the power drill.