The Essence Companion only really talks about guilds and universities in general terms, and in the context of learning spell lists more than anything else. So there may be useful ideas there, but the ideas are not really concrete in terms of guild organisation.
*****
JUNKdeLUXE, if you don't mind waiting a month or two, I would be more than happy to write something up using a combination of inspirations, from RM2, RMSS/RMFRP, and elsewhere, for an article for the Guild Companion Magazine. How does that sound to you? (I'll wait till you've replied before starting on it.)