It's hilarious the kind of ego trolls have nowadays. You're just this little kid sitting in his mothers house thinking he'll try to sound like a big man on a subpar forum :3 Good job at that kiddo.
Anyhow, I signed up because I wanted to play with an inverted controller, not to get in an argument with children.
Xpadder does work to reverse the mouse, however you lose rumble. If you're uisng Win7, you also have to unzip, then run in compatibility mode to set up the controller. Then keep the program running while playing ArmA 2. Sadly, the game doesn't operate the best with controllers, especially in single player, as you can't give commands very easily/buttons with Xpadder seem to work quite strange with ArmA2. I've gone back to running with a mouse and keyboard, which seems to (obviously) be the best setup for this game...would have been nice to sit back in a more comfortable chair and play though haha.
Figured I'd give the solution to anyone that still wanted to try this out. Oh right, you also have to go into the right stick and set it up as inverted mouse. Note that this will also cause the stick to control your mouse out of game, too, which is... fun.
Enjoy.