var $j = jQuery.noConflict();

jQuery.preloadImages = function()
{
  for(var i = 0; i<arguments.length; i++)
  {
    jQuery("<img>").attr("src", arguments[i]);
  }
}

$j.preloadImages("images/preview_1.jpg","images/1.jpg","images/preview_2.jpg","images/2.jpg","images/preview_3.jpg","images/3.jpg");