Took me forever to, you have to use the mount to make the jump from the big rock on the right side of the house to the roof and then dismount and gingerly walk the railing to the scrying stone. At least that's how I finally did it
Okay it took me running through it 6 times, but it finally worked, I still lost my cleric companion but the quest did what it was supposed to so I guess there is a chance it will work with enough tries
I ran into the problem where Zami was not even in the instance and when I tried to logout and back in I was thrown under the world. This quest is horribly bugged