In the Slaughter House level (the level about the web-broadcast), there are many pesky sentry guns. To keep from getting annihilated by them, use flares. You can find five of them close together. Rolling seems to work best in avoiding the guns. Roll just outside of the gun's quarter-turn area so you are close enough to reach the computer control. Light a flare and throw it in a way that will allow you safe passage to the computer, then disable the gun. Be careful -- the flare only distracts it just enough to give you a small time frame to get to the computer.

When you make it to the end of the level and are near the three soldiers and the three Chinese diplomats, you will see two sentry guns protecting the entrances. Set up wall mines (if available) on the side of the room opposite the doors. This is a trap for the soldiers that appear later. Turn back to the two sentry guns. The one on the left is guarding the soldiers. You want to leave the gun on, but make sure the circle next to "Disable IFF" is not filled in. This will set the gun to attack anyone (namely the enemies that try to kill your fellow soldiers). Disable the gun on the right and also make sure the IFF circle is not filled in. Once you enter and talk to the Chinese diplomat, you will be alerted that Grinko is coming. Exit out of the room, turn on the gun you just disabled, and start aiming across the room. You will see multiple soldiers approaching. A lot of them will be blown up, or catch fire and die. Watch for ones with frag grenades. Once the other soldiers are dead, Grinko can be easily dealt with. Keep some cover and start looking for a little head popping up above the wooden partitions then shoot him in the face (or use a frag grenade if available). Once Grinko is dead, disable the gun on the left and you will have completed the mission.