On the right side of CrossFire there's a house with a big hole on the side. Go in.

Go outside the hole. There is a little line.

Go on top. There is a railing on the side.jump on it (must have old school).

There you'll find a big chuck of the wall. There is a little blanket.

Jump on it as well. Then you see the roof.

And there! If you need help add me as your buddy.