By the way I was ably to bypass this little situation by killing all the snake women and stealing their stuff. Got my two rings. I do have another issue now but that will be posted in another thread.
I know this is an oooold post but have just gotten into this game (loved ultima and the underworlds). I've got the same problem: I accidentally killed the snake women (they were hostile to me for breaking into their store room). Anyway, I now need Zohark and there are no snake women - let alone queen - to talk to. Is there any way of getting Zohark without speaking to them? You say you could bypass the situation...
I also don't have save games for before I killed them, I didn't know they were integral to the plot! I'm on Arx-Liberatis.
UPDATE: Actually, I got past it. So on one of the corpses of the snake women should be an orb of some sort. You need to activate this with the door switch just outside the snake women's area on lvl 6 (the switch allows you to deactivate the field blocking access to the trial to get Korhaz).