This works best when playing co-op.

Right before you tell the guy on the radio to come and rescue you get ready and grab some ammo. Tell the guy to rescue you and quickly run with your partner past the dock to the corner (where the big rock is at the right) and go to the corner and try to jump on it. It is hard to do this so it may take a few tries.

After you have gotten on the rock crouch down and wait. Have your partner melee you so you wont get pulled by a smoker.

When the tank comes let your other team mates kill it.

When the boat arrives throw a pipebomb far away and run to the dock. This will have you save a few seconds.