§1. The anointings with the words, order, and manner prescribed in the liturgical books are to be performed carefully. In a case of necessity, however, a single anointing on the forehead or even on some other part of the body is sufficient, while the entire formula is said.
§2. The minister is to perform the anointings with his own hand, unless a grave reason warrants the use of an instrument.
Source: Code of Canon Law (Vatican.va)