Sample Initiation Script for Major Magical Focus (spirits).
The Script calls for the Mystagogue to spend a season teaching the student different ways of interacting with spirits. The initiation Quest involved a journey in the caverns below Hedyosmos, wherein the initiate enlists the aid of one of the shades below to find a specific, lightness chamber, and there offer vis in a ritual that is part invocation, part sacrifice, part warding.
Pre2 + Cult Lore 7 (given 6 is the minimum for the "inner circle" and his Mystagogue is the most prominent member of the Titanoi in the Tribunal, I think Tisiphon, who would serve as Mystatogue, would qualify for at least 7 ranks).
+3 Minor Virtue to Major Virtue
+3 Mystagogue Sacrifices Time
+3 Initiation Quest (described above)
+2 Sympathetic Bonus (Caverns of Hedyosmos)
+1 Misc (Sacrifice of Wealth, I will happily spend some of my starting vis on this if needed)
This gets to 21, the level needed for a Major Virtue known to the Mystagogue.