movieclip not sprite

[WWFC]

hi all,

i am hoping someone can give me a clue on how to swap the sprite instance for a movieclip via the document class.

this a boid example from soulwire, and works great but i want to use a library clip instead of the vector sprite - for arguments sake - the library clip would be "boid"...

package  
{
    import soulwire.ai.Boid;

    import flash.display.Sprite;
    import flash.events.Event;
    import flash.geom.Vector3D;

    /**
     * Demo
     */

    [SWF(width="800", height="600", backgroundColor="#FFFFFF", frameRate="31")]
    public class AbstractDemo extends Sprite 
    {
        protected var _boids : Vector.<Boid> = new Vector.<Boid>();
        protected var _boidHolder : Sprite;

        protected var _config : Object = {
                                            minForce:3.0,
                                            maxForce:6.0,
                                            minSpeed:6.0,
                                            maxSpeed:12.0,
                                            minWanderDistance:10.0,
                                            maxWanderDistance:100.0,
                                            minWanderRadius:5.0,
                                            maxWanderRadius:20.0,
                                            minWanderStep:0.1,
                                            maxWanderStep:0.9,
                                            boundsRadius:250,
                                            numBoids:120
                                            };

        public function AbstractDemo()
        {
            _boidHolder = addChild(new Sprite()) as Sprite;
            addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
        }
        
        protected function init():void
        {
            // Init
        }

        protected function createBoid() : Boid
        {
            var boid : Boid = new Boid();
            
            setProperties(boid);
            boid.renderData = boid.createDebugShape( 000000, 4.0, 2.0);
            
            _boids.push(boid);
            _boidHolder.addChild(boid.renderData);
            
            return boid;
        }

        protected function createBoids(count : int):void
        {
            for (var i : int = 0;i < count; i++)
            {
                createBoid();
            }
        }

        protected function setProperties(boid : Boid) : void
        {
            boid.edgeBehavior = Boid.EDGE_BOUNCE;
            boid.maxForce = random(_config.minForce, _config.maxForce);
            boid.maxSpeed = random(_config.minSpeed, _config.maxSpeed);
            boid.wanderDistance = random(_config.minWanderDistance, _config.maxWanderDistance);
            boid.wanderRadius = random(_config.minWanderRadius, _config.maxWanderRadius);
            boid.wanderStep = random(_config.minWanderStep, _config.maxWanderStep);
            boid.boundsRadius = stage.stageWidth * 0.6;
            boid.boundsCentre = new Vector3D(stage.stageWidth >> 1, stage.stageHeight >> 1, 0.0);
            
            if(boid.x == 0 && boid.y == 0)
            {
                boid.x = boid.boundsCentre.x + random(-100, 100);
                boid.y = boid.boundsCentre.y + random(-100, 100);
                boid.z = random(-100, 100);
                
                var vel : Vector3D = new Vector3D(random(-2, 2), random(-2, 2), random(-2, 2));
                boid.velocity.incrementBy(vel);
            }
        }

        protected function random( min : Number, max : Number = NaN ) : Number
        {
            if ( isNaN(max) )
            {
                max = min;
                min = 0;
            }
            
            return Math.random() * ( max - min ) + min;
        }

        protected function updateBoid(boid : Boid, index : int) : void
        {
            // Override
        }

        protected function step(event : Event = null) : void
        {
            for (var i : int = 0;i < _boids.length; i++)
            {
                updateBoid(_boids[i], i);
            }
        }

        protected function onAddedToStage(event : Event) : void
        {
            removeEventListener(Event.ADDED_TO_STAGE, onAddedToStage);
            addEventListener(Event.ENTER_FRAME, step);
            init();
        }
    }
} 

i know that i need to add

    import flash.display.Movieclip; 

but am not able to work out what i need to add/edit...

any ideas folks?