Here’s a quick small utility class that you can use as a starting point to build a keyboard tracker to handle Copy, Paste, Cut, Undo, Redo etc operations from the user.

package utils
{
	public final class KeyBoardCombination
	{
		public static const UNDO:int  = 0;
		public static const REDO:int  = 1;
		public static const CUT:int   = 2;
		public static const PASTE:int = 3;
		public static const COPY:int  = 4;

		public static function  get getCombinationCollection():Vector.<array>
		{
			var combinationCollection:Vector.<array> = new Vector.<array>();
			combinationCollection.push( new Array( 17, 90 ) );
			combinationCollection.push( new Array( 17, 16, 90 ) );
			combinationCollection.push( new Array( 17, 88 ) );
			combinationCollection.push( new Array( 17, 86 ) );
			combinationCollection.push( new Array(17, 67) );

			return combinationCollection;
		}

		public static function checkKeyboardCombination(keyboardPressedCollection:Array):int
		{
			var retCombinationState:int = -1;
			var combinationLength:int;
			var confirmedKeys:int = 0;
			var combinationCollection:Vector.<array> = KeyBoardCombination.getCombinationCollection;

			combinationCollection.forEach(function callback(combination:Array, selectedState:int, combinationCollection:Vector.<array>):void{

				confirmedKeys = 0;

				combination.forEach( function callback(checkKey:int, index:int, array:Array):void {

					combinationLength = combination.length+1;

					keyboardPressedCollection.forEach(function callback(keyPressed:int, idx:int, arr:Array):void {

						if (keyPressed == checkKey)
							confirmedKeys++;
					});

					if (confirmedKeys == combinationLength-1)
						retCombinationState = selectedState;
				});
			});

			return retCombinationState;
		}
	}
}

Implementation looks like this:

private var keyboardCollectionPressed:Array = new Array();
			mainView.stage.addEventListener(KeyboardEvent.KEY_DOWN, function(event:KeyboardEvent):void {
				keyboardCollectionPressed.push( event.keyCode );
			} );
			mainView.stage.addEventListener(KeyboardEvent.KEY_UP, onKeyboardUp);

		private function onKeyboardUp(event:KeyboardEvent):void
		{
			var combination:int = KeyBoardCombination.checkKeyboardCombination( keyboardCollectionPressed );

			switch (combination)
			{
				case KeyBoardCombination.UNDO:
					trace("UNDO");
					break;
				case KeyBoardCombination.REDO:
					trace("REDO");
					break;
				case KeyBoardCombination.CUT:
					trace("CUT");
					break;
				case KeyBoardCombination.PASTE:
					trace("PASTE");
					break;
				case KeyBoardCombination.COPY:
					trace("COPY");
					break;
			}

			keyboardCollectionPressed = new Array();
		}