Well, we're not strictly talking about the mod, but I think everyone thought you were talking about it in your first post, before you edited it right when you posted your last one.
Well, turn off autoaim for both players and play as Oddjob will get you cheap kills....
Also remember by pressing the sidestep buttons (C-left and C-right per default) while aiming you'll strafe from your cover, letting go will bring you back to your default position. You even might want to kneel and shoot the feet of your opponent (press Aim and C-down and let go simultaneously) while being harder to hit yourself. As said before knowing which weapons can penetrate glass or doors will help you a lot - spamming Moonraker through doors and stuff sure is helpful.
If you own a Source game (Counterstrike: Source, Half Life 2 or such) you'll might want to give this mod a try after all.
Here's what this mod is about:
http://www.youtube.com/v/swhFBPDGZXc(watch on youtube for higher resolution)