Barker's second novel, Flamesong, has the most information about Mihalli.
Yes, I've been thinking of buying some of his novels for quite a while now. I guess it's just a matter of money right now. Being broke sucks.
(but see Flamesong for a Mihalli trap!)
I understand that you don't want to ruin the book for other people, but if you could PM me about it you would have no less than a Medium Favor to collect from me! (I don't think it would keep me from buy and read the book anyway)
If you need legendary inspiration, consider borrowing from ancient myths. I imagine the myths of ancient India, China, or elsewhere in Asia would fit pretty well with just a few name changes.
Great advice - thats really something worth contemplate a little.
Mihalli could have the role as the trickster, like Loke in nordic mythology. He often change shapes to trick and win advantages (but usually don't end up as a winner, despite this). There is some tales about the indian gods, especially Hanuman (but Tékumel doesn't have any monkeys!

) and Ganesha (a chlén-headed demon, anyone?

), that I really like. The legendary Mihalli could also be a mysterious advisor to Hrugga (as you mentioned), with similarities to the epic of Gilgamesh.
One is Ngala, a more or less ruined city to the west that is a special holy site for Dlamelish and Hrihayal.
This is hilarious!
The characters of my campaign is in N'gala right now. At a whim I moved N'gala to the coast, more or less where the ruined fortress (of Hrugga) is now, and let the characters ship, a hrú called Little Rainbow, be sucked in to the ruins by some twisted weather magic. They are right in some sinister trap right now, not knowing how to get out of it. In the djungle inland awaits Yugao, ripped from The Temple of the Doomed Prince here on this site, and with him the presence of his terrible godess (whos name should not be mentioned!). I would let you have a glimpse of my chronicle, but the forum where I've posted it is down for the moment (and I guess you can't understand swedish anyway...). It got a foreword by Lord Ksárul, who acts as the narrator, that I'm particulary satisfied with (one of the 10 keys to his prison is hidden in Yugao's lair (an ancient temple of unknown origin) - his godess have tried to figure it out, but the concept of a key is something to abstract for her alien mind).
Oh. Sorry. Got a little carried away there...
You seem to be part of the same mail list as my buddy, who I got the information about N'gala from in the first place.
(search the Blue Room archive on this site for more about him)
Yes, I have only just begun to tap the information available there, I guess.
hope this helps
Sure!