Its possible to jump into the rock outcrop he idles over with the Level 15 mount, you just have to hit it right. 

Another way to get him, if you're lucky enough to be a soldier, is to head down to the camp to the southwest, and grab a sniper shot out of the lockbox. Effortless!

Saw some people asking in /z How to get him. Sometimes he seems to sit just in one place, Seems it is only when he has recently spawned. After a While he starts Flying around. Two places you can pick him up. either side of him the mountain to his North with a Ranged Class. I did on my stalker on the small hill /slope to his west. He flies really low there and just jump and try to get his attention that way. It works