Plan for the Big Heist
1) Activate the Old Way using the Glass of Time. It is located inside the Imperial Palace. I do not know what it looks like or exactly where to find it.
2) Find the entrance to the Old Way. It is rumored to be somewhere in the sewers under the Imperial City.
3) Inside the Old Way is an entrance to the heart of the Imperial Palace. Savilla's Stone was only able to scry the two most important obstacles. For one of them you will need to use the Boots of Springheel Jak.
4) To enter the Imperial City you must use the Arrow of Extrication to to unlock the final door.
5) Inside the Imperial Palace you must find the Imperial Library. On the bottom floor is some sort of viewing room.
6) I have arranged to have a particular scroll made available in the Chamber. The blind monks that care for the scrolls are expecting Celia Camoran, but you will take her place. Just find the chair assigned to visitors to the library. You must not speak, or they will know it is not her. Just let them bring you the scroll.
7) Once you have the scroll, retrace your steps and deliver it to me. Of course the chances of something going wrong with this plan are very high. When that happens, you'll just have to get creative.