<?php
class TamkaAutoload
{

  function loadApplicationClasses () {

  /*** nullify existing autoloads ***/
  spl_autoload_register (null, false);

  /*** specify extensions that may be loaded ***/
  spl_autoload_extensions('.php');

  function TamkaLoader ($class)
  {                           
   /*** retrieve namespaces and folders from configuration ***/
   $serverConfig = new TamkaServer;                    
   $namespaceArray = explode(",", $serverConfig->autoloadNamespaces);

   $autoloadFolderArray = explode(",", $serverConfig->autoloadFolders);                               

   /*** process each configuration name space ***/
   for ($na = 0; $na < count($namespaceArray); $na++) {

    /*** remove name space value from class to find filename ***/
    $classFilename = TamkaAutoLoad::extractFileName ($class, $namespaceArray[$na]);

    if ($classFilename == false) {
      /*** namespace not used for class prefix ***/
    } else {
      /*** namespace matches ***/

      for ($fa = 0; $fa < count($autoloadFolderArray); $fa++) {
      /*** namespace not used for class prefix ***/
        $folderFile = TamkaAutoload::replaceSlashwithDirectorySeparator(TAMKA_BASE.trim($autoloadFolderArray[$fa]).DS.$classFilename);

        /*** require_once file, if exists, and exist ***/
        $results = TamkaAutoLoad::requireFilename ($folderFile);                                         

        if ($results == true) {
         $fa = count($autoloadFolderArray) + 1;
         $na = count($namespaceArray) + 1;
        }
       } 
      }
     }
    }

  /*** register the new loader function ***/
  spl_autoload_register('TamkaLoader');               

  /*** RELOAD the Joomla! Autoload ***/
  spl_autoload_register('__autoload');                            
  }       

  function extractFileName ($class, $namespace) 
  {
    if (substr($class, 0, strlen($namespace)) == $namespace) {
      return trim(substr($class, strlen($namespace), (strlen($class) - strlen($namespace)))).'.php';
    } else {
      return false;
    }
  }

  function replaceSlashwithDirectorySeparator ($filename) 
  {  
    return str_replace (chr(47), DS, $filename );      
  }                        
  function requireFilename ($file) 
  {  
    if (file_exists($file)) {
      require_once $file;
      return true;
    } else {
      return false;
    }
  }    
}

<?php
class TamkaAutoload
{

  function loadApplicationClasses () {

  /*** nullify existing autoloads ***/
  spl_autoload_register (null, false);

  /*** specify extensions that may be loaded ***/
  spl_autoload_extensions('.php');

  function TamkaLoader ($class)
  {                           
   /*** retrieve namespaces and folders from configuration ***/
   $serverConfig = new TamkaServer;                    
   $namespaceArray = explode(",", $serverConfig->autoloadNamespaces);

   $autoloadFolderArray = explode(",", $serverConfig->autoloadFolders);                               

   /*** process each configuration name space ***/
   for ($na = 0; $na < count($namespaceArray); $na++) {

    /*** remove name space value from class to find filename ***/
    $classFilename = TamkaAutoLoad::extractFileName ($class, $namespaceArray[$na]);

    if ($classFilename == false) {
      /*** namespace not used for class prefix ***/
    } else {
      /*** namespace matches ***/

      for ($fa = 0; $fa < count($autoloadFolderArray); $fa++) {
      /*** namespace not used for class prefix ***/
        $folderFile = TamkaAutoload::replaceSlashwithDirectorySeparator(TAMKA_BASE.trim($autoloadFolderArray[$fa]).DS.$classFilename);

        /*** require_once file, if exists, and exist ***/
        $results = TamkaAutoLoad::requireFilename ($folderFile);                                         

        if ($results == true) {
         $fa < count($folderArray) + 1;
         $na = count($namespaceArray) + 1;
        }
       } 
      }
     }
    }

  /*** register the new loader function ***/
  spl_autoload_register('TamkaLoader');               

  /*** RELOAD the Joomla! Autoload ***/
  spl_autoload_register('__autoload');                            
  }       

  function extractFileName ($class, $namespace) 
  {
    if (substr($class, 0, strlen($namespace)) == $namespace) {
      return trim(substr($class, strlen($namespace), (strlen($class) - strlen($namespace)))).'.php';
    } else {
      return false;
    }
  }

  function replaceSlashwithDirectorySeparator ($filename) 
  {  
    return str_replace (chr(47), DS, $filename );      
  }                        
  function requireFilename ($file) 
  {  
    if (file_exists($file)) {
      require_once $file;
      return true;
    } else {
      return false;
    }
  }    
}

http://www.alltogetherasawhole.org/profiles/blogs/joomla-autoloader-using

Autoload for PHP that enables the definition of namespaces and folders in a list that is used in the spl_registered function for any number of unknown values. This specific function can be used with Joomla! 1.5 since it reload's Joomla!'s autoload class at conclusion.

PHP Autoloader with spl_autoload

PHP