Spaz's Guide To Nearly Killing Yourself.
Step 1: Travel to Area 69. A vehicle is helpful, but if you like living dangerously pressing the left analog stick up and tapping X will work.
Step 2: Get right up to the gate. If you haven't pissed them off yet, good job.
Step 3: Did I mention you have to break through a gate? Well, you do. If you don't already have a vehicle do something to get a wanted level.
step 4: Now that you have these pissed off people, in cars, with guns, after you, wait for one to exit his car and attempt to kill you.
Step 5: Has he exited his car? No, he just parked it? Ok, another second or so. Alright, run like hell to the car! Get in it! Now drive drive drive!
Step 6: Smash through the gate, might mess you up a bit with a bunch of FBI guys ramming you, but hey, you're through the gate, right?
Step 7: Keep driving, don't stop for ANYTHING! All the way in the back of that long row of gated off area is where you want to be.
Step 8: To your left is a Hunter, followed by a hangar, and there's a Hydra ahead of you. Right before the Hydra is a SECOND hangar((there's three)). That's the one you want.
Step 9: Board the Rhino. Must I explain what to do next?