This basically uses the glitch described by Somn in this thread : http://www.ownedcore.com/forums/worl...isconnect.html ([Glitch] Mount/Mushroom Through Walls in 4.3 (without disconnect))
This means that you will need the mushroom chair from FL dailies and a size increasing item.
Edit: If you're a mage, you can blink through the spot without the item requirements.