I'm not positive, I just assumed that was the whole reasoning behind the phrase "Come seek me out when you have the same eyes as me", otherwise any Uchiha with a mangekyou could take the eyes of one of their fallen comrades and make it an EMS. Also Itachi could have taken the eyes of any one of the Uchiha he killed and given himself an EMS.
As for Kakashi, if my theory is correct, I don't think he can implant a Sharingan in his left eye, activate mangekyou, and then move it to his right eye.