[AlexanderHowl]

You can adapt standard magic to Path/Book without that much effort by having each College being a separate Book. If you are using Effect Shaping, the Prerequisite Count becomes the ritual default penalty. If you are using Energy Accumulation, the Prerequisite Count plus 5 becomes the Energy Requirement. You would have to modify some spells, but it should be workable.

It becomes tricky in the case of Enchantments, but I would suggest transforming the energy requirement into (hours of ritual preparation/[5×mages]) for Quick and Dirty Enchantment (with the normal penalties and the minimum effective skill 15) or (days of ritual preparation) for Slow and Sure (with the normal restrictions and the minimum effective skill 15). In the case of magical items that allow the casting of a spell, they instead allow the casting of the ritual at skill of the item. You would have to modify some enchantments, but it could be workable.