I can't imagine a faster way to get there then the helicopter described above (I just used the cheetah they gave you)-- when you get there just be methodical-- get all the windows on the upper level (on your map/HUD the ones on your level will be square--the ones below you will have a down pointing triangle) and then do the bottom level--and a little trick--tap your sprint button quickly as you run and he won't get tired. Just keep pausing and looking at your map (you can zoom in on it to see what you have left to do)
I used a ruger or M4 I think--I like using an non auto aim rifle for this one, whatever you use, make sure you have plenty of ammo.
I've hear of people using grenades or rocketlauncher too--I'm not sure how effective they are but the rocket launcher might work real well with its long range (just don't hurt yourself).