1. First off you can either do the switch jump or the kung fu flip to do the sky diver.
(To do the switch jump you take out your pistol. Go near a place you can take cover and as quick as you can switch to your shotgun right before you press A to take cover.)
2. Then do skydiver onto a truck. (Force Mount or anything you like to use to do it) But when you get into skydiver, you should hold up and you will have the jump over icon. So why not jump an extra bit higher?

Alright I know that it isn't the most useful thing, but hey it's a glitch people so go submit some of your own if you think otherwise haha.

*Credit for the glitch goes to Scrubs 122 for help with the glitch*