Really, the process depends on the diocese and/or parish. If I were you, I’d ask your pastor what the process is at your parish. Usually, there’s some type of training involved, and the need to make sure that you are living in accordance to Church teachings (as to not commit the sin of scandal and/or sacrilege). If your pastor isn’t in charge of trainings, he knows who is, and will give you that person’s contact information. And - to note - there is no requirement that parishes even have EMHCs. EMHCs are for convenience matters only (to speed up the communion procession), but, remember, the Ordinary Ministers of Holy Communion are ordained clergy, and the pastor can make the decision not to use EMHCs.