Well, I can barely remember that quest but I may have a solution.
This method can be very useful for getting beyond locked doors or around walls:
Get a bowl, yes, a bowl.
Put it on the ground in front of the object you want to pass through
use the whirlwind sprint while having your crosshairs on the bowl.
If you do that correctly you will be on the other side of the object/door/wall (Note: save before attempting as you could get yourself stuck, which is a big problem on consoles because there's no developer console)
If I remember correctly, you should be able to go around his visible point, though, to continue on with the quest you would have to get caught.