Friction to motion from keyboard

Below is my code. Most of this was code I found online but modified to use more space. How would apply velocity to the keyboard actions in this code?

package{

import flash.display.Sprite;

import flash.events.*;

import flash.events.KeyboardEvent;

import flash.geom.Rectangle;

import util.MouseSpeed;

import flash.ui.Keyboard;

[SWF(width="800", height="600", frameRate="30", backgroundColor="#FFFFFF")]

public class ScrollByDrag extends Sprite

{

    var ms:MouseSpeed=new MouseSpeed();

    var xSpeed:Number=0;

    var ySpeed:Number=0;

    var friction:Number=0.96;

    var offsetX:Number=0;

    var offsetY:Number=0;

    var bounds:Rectangle;

    //clip we are going scroll by dragging

    var content:Sprite;

    /**

     * Constructor

     */

    public function ScrollByDrag()

    {

        addEventListener(Event.ADDED_TO_STAGE, onAddedToStage);

    }

    /**

     * Display object has been added to the on stage display list

     * @param event

     */

     private function onAddedToStage(event:Event):void

    {

        init();

    }

    /**

     * Create stage assets to scroll and add to the display list.

     */

    private function init():void

    {

        //draw test content to scroll by dragging

        var circ:Sprite=new Sprite;

        circ.graphics.beginFill(0x000000);

        circ.graphics.drawRect(500,200,600,25);

        circ.graphics.endFill();

        content=new Sprite();

        addChild(content);

        content.graphics.beginFill(0xFFFFF3);

        content.graphics.drawRect(0, 144, stage.stageWidth, 112);

        content.graphics.endFill();

        content.addChild(circ);

        content.buttonMode=true;

        content.useHandCursor=false;

        circ.useHandCursor=false;

        //define the bounds of how far we can drag the content.

        bounds=new Rectangle(stage.stageWidth - content.width, content.y, content.width);

        //handlers

        content.addEventListener(MouseEvent.MOUSE_DOWN, mouseDownHandler);

        content.addEventListener(Event.ENTER_FRAME, throwcontent);

        stage.addEventListener(KeyboardEvent.KEY_DOWN, throwcontentKey);

    }

    /**

     * Mouse button is pressed

     * @param e

     */

    private function mouseDownHandler(e:Event):void

    {

            stage.addEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);

            offsetX=mouseX - content.x;

            startScroll();

    }

    /**

     * Mouse button is released

     * @param e

     */

    private function mouseUpHandler(e:MouseEvent):void

    {

        stage.removeEventListener(MouseEvent.MOUSE_UP, mouseUpHandler);

        xSpeed=ms.getXSpeed();

        stopScroll();

    }

    /**

     * Drag the content

     */

    private function startScroll():void

    {

        content.startDrag(false, bounds);

    }

    /**

     * Stop dragging the content

     */

    private function stopScroll():void

    {

        content.stopDrag();

    }

    /**

     * Apply inertia when we stop dragging the content

     * @param e

     */

  private function throwcontent(e:Event):void

    {

          // move content and apply friction

        content.x+=xSpeed;

        content.y+=ySpeed;

        xSpeed*=friction;

        ySpeed*=friction;

        if (content.x > 0)

        {

            content.x=0

        }

        if ((content.x + content.width) < stage.stageWidth)

        {

            content.x=stage.stageWidth - content.width;

        }

    }

    private function throwcontentKey(e:KeyboardEvent):void

    {

        // move content and apply friction

            if (e.keyCode==Keyboard.LEFT)

            {

                content.x-=50;

                if (content.x > 0)

                {

                    content.x=0;

                }

                if ((content.x + content.width) <= stage.stageWidth)

                {

                    content.x=stage.stageWidth - content.width;

                }

            }

            if (e.keyCode==Keyboard.RIGHT)

            {

                content.x+=50;

                if (content.x > 0)

                {

                    content.x=0;

                }

                if ((content.x + content.width) <= stage.stageWidth)

                {

                    content.x=stage.stageWidth - content.width;

                }

            }

    }

}

}