I’ve been running Sidereals with College-based Charms for years with ease. The trick was I basically turned Colleges into Excellencies.
Basically if you had a College you could spend 1m per dot of College. It costs 1m per die, 2m per success which you could add to your own action or the action of anyone in line of sight whose actions where thematic for the college. You could also subtract one die or one success for the same cost.
Sidereals didn’t get an I(A)M variant, but could create Astrological Blessings and Curses which basically had the same effect. “Yeah, I want to give everyone in the army a +2 die bonus when fighting Wyld mutants.”
“Cool. Roll Performance to contact the Pattern Spiders and then Linguistics to craft your prediction. Difficulty 2 on both rolls because you are using College 2 and add 4 for the Magnitude of the effect. You want it to be one scene so that’s Difficulty +1 as well.”