I have finished the coop mission several times. The easiest way is to drive straight into the first building on left of road. Drive thru the crumbled wall or if you miss, knock a wall down, get out, and enter building.
Gunner takes out the guy in the sand bags checkpoint on the way in to town, than as the driver is on his way to the building on foot, take out the couple that show up on the left on top of hill. Once the driver gets inside the building he runs thru and guards that side of the building.
Gunner than gets out and throws a grenade around the left of the building killing one or two there.
The one in the forward doorway will now proceed to gun down about 30 some AI that come into his view running down the road. The gunner in the rear than peeks around the corner, next to the road, picking on the ones running down the road and the flankers to the right that forward guy missed, Â and its a bloody turkey shoot from there.
Getting the SAW is a must, cause the amount of enemy troops would overwhelm a 20 round magazine :P
One Brdm or two coming in is no problem, just shoot the tires out.
No need to get in Brdm now. Just clear the rest of the city going building to building picking out on the few that are left. They usually stay in the same spot every time. So learn their positions and you should have good time. With 2 people we beat the map without getting a Brdm on veteran.
edit: The AI usually get killed unfortunately, but they help draw enemy into our crossfire. I have them spread out in front of town blasting away.