To complete the "King of the Buzzard World" challenge you need to get the to top of the Buzzard Academy. How do you do that?
You can get to the top of the buzzard academy by following a simple path, once you ignore some of the false starts offered to you.
To start, head to a launchpad in the northwestern corner of the Buzzard Academy.
Here is the launchpad, standing between two buildings; in front of the alarm in this area for the "Positive Reinforcements" challenge.
Once on the platform, face southwest and jump on the crate (labeled 1 in the picture), turn to your left and jump on the platform (labeled 2), and then on top of the crates here (labeled 3).
From here, jump on the flat platform to your right. In front of you is a large curved surface. Take a running jump to get up on top of it. If you jump too late you may hit the side and not get on top, just try again until you get it. This jump is what caused me to abandon this approach the first time I tried it and why I'm writing this up :)
Once you're on top, turn to your right and jump on to this slightly higher roof. When I did this, three buzzards came out to try to persuade me from continuing to my goal, take them out and continue over to the loot commode. Either on the slightly larger roof or in front of the commode you'll get the notification that you completed the challenge.