I want to get into the chest under the hall of elements. It has a sigil stone and I need one (I didnt know how to reverse the unbound dremora bug and I was to far into the game to go back to an old save) So I want a sigil.

Now how many boxes do I need? I've seen vids of this being done, but its usually just on PC. I cant seem to fall on a flat surface since the boxes are always angled. So its hard to jump from box to box.

You mean the Unbound Dremora that stays there after you complete the quest?

No my conjured minion killed him before he finished talking that means he wont spawn any more no matter how often I summon him. So I am using this exploit to get the sigil.