Shadows are the evil in all life; therefor, to link with your shadow, and control it and others, you must swear your soul to evil. This ritual is not good for you, your body, and your soul. This ritual can cause physical harm to you and, most likely, others; it will change your thoughts, make you evil; even tear your soul to pieces. This ritual should not, and will not, be treated lightly.
In the process of forging your shadow and soul you must first break your own soul, via an act of true evil. Once the soul is fragmented you must let the shadow, the evil, in and allow it to fill in the fragmented parts of your soul, completing you. After the connection has been made, you will become a single being, your soul and your shadow. This connection can then be used to control shadows, and even other people. This connection is permanent, there is no cure.