I'm testing something out with the Litancy of Larcency quest, but I need to get a follower inside of Snow Veil Sanctum. I'm on the 360, so I can't voodoo magic NPCs where I want them to go. I've already completed the quest there for the Thieves Guild, but my follower refuses to follow me into that map. I tried casting fury on them and having them attack me, in hopes that they would chase me isndie, but that hasn't worked. Tried attacking them and casting fear in hopes that they would run in on their own, but that also didn't work. I then tried numerous combinations of talking to them and running inside, hoping that - like NPCs usually do - they would chase me inside to say something else. Nothing worked.

Is it simply impossible to get a follower inside that place?

Yes, it's designed so that only you and Mercer can encounter Karliah, and is a Thieves Guild zone.
It was a bad move on the designer's part to also use it for the Jarl's quest.

I guess my plan won't work, then. Especially since it happens again with the eye of the falmer. I wanted to have my follower steal all of the quest items, so that if I decided to complete the Thieves Guild, I could hopefully wait for a patch and then take the items from them to start, and then complete, the quest. That's the key, as if the follower steals the items, the quest doesn't officially start. I did the same thing with the glitched musical bard items.

But as I've said, it's a moot point, since two of the items are in areas where followers can't go.