How to add preloader to an existing swf??

Question

how do i add a preloader to an already made swf?
also, do i have the preloader open up in seperate html file.
don't want to buy any programs to do this.
i did try it by just changing the file names to preloader file name to load the swf.
but it push all the content over to the right side of the screen.

Answer 1

Ok still verifying that it is not stopping the way I expect. It starts before loader reaches 100%, the funny thing is though, I can see it faded in the background. Wonder if it has anything to do with code in the SWFLOADER.swf file. Here's the code:
import flash.geom.*
import flash.display.* 
var loadurl:String = "nebphotoflash/new_intro4.swf";
var nDepth:Number = 0;
var nWidth:Number = 200;
var nHeight:Number = 20;
var nPadding:Number = 3;
var cLoader:MovieClipLoader = new MovieClipLoader();
var oListener:Object = {onLoadInit:onContentLoaded};
var mcLoader:MovieClip = this.createEmptyMovieClip("Loader_MC", 0);
var mcContent:MovieClip = this.createEmptyMovieClip("Content_MC", 1);
var mcLoadBarBg:MovieClip = mcLoader.createEmptyMovieClip("LoadBarBg_MC", nDepth++);
var mcLoadBar:MovieClip = null; //Duplicated later with mcLoadBarBg
var txtPercLoad:TextField = null; //Create after duplication
var cMatrix:Matrix = new Matrix();
mcLoader._alpha = 0;
cMatrix.createGradientBox(nWidth, nHeight, 0, nPadding, nPadding);
cLoader.addListener(oListener);
mcLoader.lineStyle(1, 0x000066, 100);
DrawRect(mcLoader, 0, 0, nWidth, nHeight);
mcLoadBarBg.lineStyle(1, 0x0000FF, 0);
mcLoadBarBg.beginGradientFill("linear", [0x006699, 0x0066FF], [100,100], [0, 255], cMatrix, SpreadMethod.PAD);
DrawRect(mcLoadBarBg, 0, 0, nWidth - nPadding*2, nHeight - nPadding*2);
mcLoadBarBg.endFill();
mcLoadBar = mcLoadBarBg.duplicateMovieClip("LoadBar_MC", nDepth++);
txtPercLoad = mcLoader.createTextField("PercLoad_TXT", nDepth++, 0, 0, nWidth, nHeight);
mcLoadBar._alpha = 80;
mcLoadBarBg._alpha = 30;
Translate(mcTextMask, nPadding, nPadding);
Translate(mcLoadBarBg, nPadding, nPadding);
Translate(mcLoadBar, nPadding, nPadding);
mcLoadBar._xscale = 0;
mcContent._alpha = 0;
mcContent._lockroot = true;
mcLoader._x = Stage.width/2 - mcLoader._width/2;
mcLoader._y = Stage.height/2 - mcLoader._height/2;
txtPercLoad._x = mcLoader._width/2 - txtPercLoad._width/2;
txtPercLoad._y = mcLoader._height/2 - txtPercLoad._height/2;
SetTextFormat(txtPercLoad, "0%");
mcLoader._alpha = 100;
cLoader.loadClip(loadurl, mcContent); 
_root.onEnterFrame = function()
   var nBytesLoaded:Number = mcContent.getBytesLoaded();
   var nBytesTotal:Number = mcContent.getBytesTotal();
   var nPercLoaded:Number = Math.round(nBytesLoaded / nBytesTotal * 100);
   if(nPercLoaded > 0)
      SetTextFormat(txtPercLoad, nPercLoaded.toString() + "%");
      mcLoadBar._xscale = nPercLoaded;
function onContentLoaded(Void):Void
   //trace(_root + "::onContentLoaded");
   SetTextFormat(txtPercLoad, "100%");
   cLoader.removeListener(oListener);
   delete _root.onEnterFrame;
   delete oListener;
   delete cLoader;
   _root.onEnterFrame = function()
      //trace(_root + "::onContentLoaded::_root.onEnterFrame");
      var nInc:Number = 5;
      mcLoader._alpha -= nInc;
      mcContent._alpha += nInc;
      if(mcLoader._alpha <= 0) startLoadedContent();
function startLoadedContent(Void):Void
   delete _root.onEnterFrame;
   mcLoader.removeMovieClip();
   mcContent._alpha = 100;
   mcContent.play();
function DrawRect(mc:MovieClip, nX:Number, nY:Number, nW:Number, nH:Number, nR:Number)
   trace("DrawRect in: " + mc);
   if(nR == undefined) nR = 6;
   mc.moveTo(nX+nR,nY);
   mc.lineTo(nX+nW-nR,nY);
   mc.curveTo(nX+nW,nY,nX+nW,nY+nR);
   mc.lineTo(nX+nW,nY+nH-nR);
   mc.curveTo(nX+nW,nY+nH,nX+nW-nR,nY+nH);
   mc.lineTo(nX+nR,nY+nH);
   mc.curveTo(nX,nY+nH,nX,nY+nH-nR);
   mc.lineTo(nX,nY+nR);
   mc.curveTo(nX,nY,nX+nR,nY);
function SetTextFormat(txtField:TextField, sText:String)
   var txtFmt:TextFormat = new TextFormat();
   sText = "Loading... " + sText;
   txtFmt.font = "Verdana";
   txtFmt.align = "center";
   txtFmt.size = 11;
   txtFmt.color = 0x000066;
   txtFmt.bold = true;
   txtField.selectable = false;
   txtField.text = sText;
   txtField.setTextFormat(txtFmt);
   txtFmt = null;
function Translate(mc:MovieClip, nX:Number, nY:Number):Void
   mc._x = nX;
   mc._y = nY;