We all know Jacob's touch gives you "powers" ( lack of a better word.) But i think that he can choose to give it to you. like if he accidently touched someone, i don't think they'd be "chosen". Like in Ab Aeterno When Jacob is beating Richard up, i don't think that did anything, but when Richard asks to live forever, Jacob touches him on the shoulder "Now that i can do." So i think that Jacob can channel his powers.