ok. i took about an hour of tries and 10 minutes in game
knife as many zombies as you can before they berserk. when they go berserk train them up by running in a four leaf clover formation in the teleporter room. if you see any dogs, knife them they are insta kill early on
once they are trained up. run around the main "pond" thing aim for the head. use all your pistol ammo. dogs are most likely 3 knife kill, still easier than knifing a normal zombie.
toss a well placed grenade to make crawlers. kill the crawlers to top of your points. to lead them out of the water, pbring the zombies around the teleporter, training them in a clover fashion again. then shank the batches safely. get 5000 points and either leave or stay, but the splash damage of the pistols is dangerous with 5 dogs right on your tail