Longevity Rituals (p. 101): Add the following sentences to the final paragraph of this section. "A Longevity Ritual performed for someone else also fails when the subject suffers from an aging crisis. If the subject is a magus and has access to the Laboratory Text, he may perform the ritual himself. (Vis usage is limited by the magus's Arts, as for a spell, which may make it impossible.) As the magus was present for the original creation of the ritual, and quite possibly assisting in it, he understands the shorthand. A subject who is not a Hermetic magus may not repeat the ritual. Any magus with access to the Laboratory Text may do this, but a magus who was not involved in the initial creation needs an accessible Laboratory Text."
Writing Laboratory Texts (p. 102): Add the following paragraph at the end of the section. "Any magus (or apprentice) who assisted in a particular Laboratory Activity understands the Laboratory Texts produced for that activity without needing to translate them, and may make generally accessible copies. This also applies to a magus who is the subject of a Longevity Ritual created by another magus, even if he does not assist. Assistants do not, however, create Laboratory Texts."
Is this clear enough?