Hmm... U want to disable the arrow control, but you still want to be able to scroll the map by moving the cursor on the border of the screen. I tried a thing, let's see how you like it:
Event-
Player 1 Presses Up
-"- Down
// Do that with all keys and players
Actions-
Stop Camera for Triggering Player
The problem is that, it triggers right after a moment you press the button, and the screen scrolls a bit. But then, it stops. A bit strange...
The other thing is, you lock the camera to a unit. But the problem is, you cannot scroll the map with the mouse too...
I don't know why you want to 'turn off' keys scroll, but if you would write it, it might help to solve your problem.
btw, this isn't really a JASS problem...