§1. The supreme moderator of an institute is to be designated by canonical election according to the norm of the constitutions.
§2. The bishop of the principal seat presides at the elections of a superior of the autonomous monastery mentioned in can. 615 and of the supreme moderator of an institute of diocesan right.
§3. Other superiors are to be constituted according to the norm of the constitutions, but in such a way that, if they are elected, they need the confirmation of a competent major superior; if they are appointed by a superior, however, a suitable consultation is to precede.
Source: Code of Canon Law (Vatican.va)