ActionScript 3 :: Flash - Keeping Mouse Within Certain Boundaries

So this one is a tricky one (for me) vital to the development of my project due to the fact that we can't directly modify the position of mouseX and mouseY - they are read-only variables. Basically, what I want to do is have a player able to move their mouse only within a certain triangular area when a specific instance is active. The latter bit I can manage just fine, however I am having trouble restricting mouse movement -- or apparent mouse movement.

Here's what I have done so far:
1. Assign a library moveclip to the mouseX and mouseY position in the Event.ENTER_FRAME event - although I acknowledge that this should be moved to Mouse.MOUSE_MOVE. (this does not matter yet)
2. Using Corey O'Neils Collision detection kit, do a hit test on the border instances of the area with the crosshair/cursor.
3. Offset the cursor appropriately, and then set a standard Boolean value to false so that the cursor will not keep bouncing back into the cursor over and over.

My problem is, I am not sure what the best way is to go about allowing mouse movement again. For what it's worth, this is to stop users from aiming in an unrealistic direction with a character in a top-down (ish) shooter.

Here is my code regarding mouse movement thus far:
import flash.ui.Mouse;
import flash.events.event
import com.coreyoneil.collision.CollisionList;
Mouse.hide();
var c:crosshair = new crosshair();
addchild(c);
var myCollisionList:CollisionList;
myCollisionList = new CollisionList(c);
[Code] .....