This technique requires a Warlock.
I noticed that if you use items that makes you grow (Winterfall water etc) on low roofs, you will shrink down to normal size, and you will still have the effect.
This is a alternative method to the mount-bug.
First, find a low roof spot, then use Demoninc Circle:Summon, then you go away from this location, and then you use your "grow" item.
When you have grown, use Demonic Circle:Teleport, and voila! You are now over the roof. (Tested myself)
Also, you might be able to help a friendly player with this, by using the Ritual of summoning spell, however, I haven't tested this, so I'm not sure.
(I searched, and afaik this isn't a repost)
-Zarugi