cerebrolator said:
I can't be more specific. I'm completely new to Glorantha so I don't know anything more than what is in the second age book. There isn't too much in there on the cults (for Orlanthi) -- only a little bit of lore regarding the gods.
You seem to know a lot about them, Lord High Munchkin. Perhaps you could list a few of the popular cults and their spells for me. I would be very grateful to have even a little bit to get me started.
I'm not Lord High Munchkin, but...
As for Orlanth, the Draconized Orlanth works pretty well as a general Orlanth cult, just file off the serial marks and exchange the two myths with, say:
The Lightbringers Quest (see http://www.glorantha.com/library/religions/cop-lightbringers.html) resonance 75%
Behaviours: Right the wrong you have done; Violence is always an option; There is always an other way
Example Rewards: Skill bonus when working with a group, Heroic Ability: Heroic Aura
Orlanth and Aroka (see http://www.herowars.com/new/myth/somemyths.html) resonance 55%
Behaviours: Fight evil dragons; Rescue the oppressed
Example Rewards: Bonus when fighting dragons; Never thirsty
Or, for a deeper look, this writeup is for an earlier version of Runequest (set in the Third Age of Glorantha), so it's decidedly unofficial and some conversion will be required, but it should do as a guideline.
http://www.poppyware.com/dunham/storm.html
As well, playing the mac/pc computer game King of Dragon Pass is a good general introduction to Orlanthi life (as well as an absorbing and fun game. I've spent ridiculous amounts of time playing that game.

It's set several hundred years into the future, but for an insular clan not much would really be different. (Other than the 'evil empire' being the Lunars rather than either of the EWF and the God Learners.) The game is probably still available here:
http://a-sharp.com/kodp/
A more official, if less crunchy, writeup (but again, for the third age) can be found at the official Glorantha website (well worth looking around on this site for general gloranthan info. Not much 2nd age specific stuff though.)
http://www.glorantha.com/library/religions/cult-orlanth.html
Hope this helps!
/Jonas