First, youve got to collect some weapons, and the shotgun is definately a handy peice for this mission.
Anyway, right when the mission starts grab the python that is in the front of the room, then kill 7-10 people, when it tells you to go kill lance, do it. Jump out and run up the little set of stairs to your right. Aim and shoot as quickly as possible. Then barely turn the corner and shoot him again, and so on and so on till you get to the roof.
Once on the roof make a quick left and grab the adrenaline pill to slow down the action a bit and run to the helipad as THX mentioned. If you need health there is some up there as well. Its pretty easy to take out lance and the other three gaurds from up there. You can use any weapon of your choice.
Run back down the stairs, if you have the spaz shotty get it out. When you get half-way down the set of stairs take aim at him and just hold down the trigger and he\'ll die at about the fourth shot.
BTW, dont worry about the dudes grabbing your money, if all goes well... they\'ll only grab about 5-10 grandl, if that. It\'s nothing a lil trip to your assetts wont fix.