Illustrator script to import a folder of SVG files into separate offset layers

importSVGFilesAsLayers.js

// Import SVG Files as Layers - Illustrator CS3 script
// Description: Imports a folder of SVG files as named layers into a new document
// Author: Robert Moggach (rob@moggach.com)
// Version: 0.0.1 on 2014-05-29


function getFolder() {
  return Folder.selectDialog('Please select the folder to be imported:', Folder('~'));
}


function importFolderAsLayers(selectedFolder) {  
  // if a folder was selected continue with action, otherwise quit
  var document;
  var mm = 2.83464567; // Metric MM converter…  
  // Set the script to work with artboard rulers  
  app.coordinateSystem = CoordinateSystem.ARTBOARDCOORDINATESYSTEM;  

  if (selectedFolder) {
    document = app.documents.add(
      DocumentColorSpace.RGB,  
      width = 720*mm,
      height = 720*mm,
    );
    
    var firstImageLayer = true;
    var newLayer;
    var thisPlacedItem;
    var posX=0;
    var posY=0;
    var count=0;

    // create document list from files in selected folder
    var imageList = selectedFolder.getFiles();
  
    for (var i = 0; i < imageList.length; i++) {
      if (imageList[i] instanceof File) {
        var fileName = imageList[i].name.toLowerCase();
        if( (fileName.indexOf(".svg") == -1) ) {
          continue;
        } else {
          if( firstImageLayer ) {
            newLayer = document.layers[0];
            firstImageLayer = false;
          } else {
            newLayer = document.layers.add();
          }
          // Give the layer the name of the image file
          newLayer.name = fileName.substring(0, fileName.indexOf(".") );
     
          // Place the image on the artboard
          newGroup = newLayer.groupItems.createFromFile( imageList[i] );
          newGroup.position = [ posX , posY ];
        }
      }
      posX += newGroup.width;
      if(posX > (newGroup.width*16)) {
        posX = 0;
        posY -= newGroup.height;
      }
    }
    if( firstImageLayer ) {
      // alert("The action has been cancelled.");
      // display error message if no supported documents were found in the designated folder
      alert("Sorry, but the designated folder does not contain any recognized image formats.\n\nPlease choose another folder.");
      document.close();
      importFolderAsLayers(getFolder());
    }
  } else {
    // alert("The action has been cancelled.");
    // display error message if no supported documents were found in the designated folder
    alert("Rerun the script and choose a folder with images.");
    //importFolderAsLayers(getFolder());
  }
}

// Start the script off
importFolderAsLayers( getFolder() );

How can i do this work on current document?