Requirements:
Epic Mount (That's it!)
What you do:
http://i36.tinypic.com/25hedc9.jpg
The first image is showing an aerial view of where you need to be standing while on your mouth, right at the edge of the shed and aiming towards the corner of the stables.
http://i33.tinypic.com/30l2zgm.jpg
This image showers a better example of where to aim for jumping.
You jump towards the edge and will stop (if aimed correctly) at the edge of the stable. Dismount here and simply jump jump once, then one more time to get onto the roof.
I know it is common knowledge to get on the roof with the boots and parachute cloak, this is just a method I use on my alts.
Cons:
Rogues can Shadowstep up to you if in LoS
If the enemy is smart and you're the only defender they can attempt to retrieve the node from under the small roof at the very edge of node capping range.
Other than that, happy healing and nuking!