====== Access template parameters in component's tmpl override ======

  class JAddons{
	static public function getTplParams(){
		$app =& JFactory::getApplication();
		$cont = null;
		$ini   = JPATH_THEMES.DS.$app->getTemplate().DS.'params.ini';
		$xml   = JPATH_THEMES.DS.$app->getTemplate().DS.'templateDetails.xml';
		jimport('joomla.filesystem.file');
		if (JFile::exists($ini)) {
			$cont = JFile::read($ini);
		} else {
			$cont = null;
		}
		return new JParameter($cont, $xml, $app->getTemplate());
	}
  }

Load the class:
  $app =& JFactory::getApplication();
  JLoader::register('JAddons', JPATH_THEMES.DS.$app->getTemplate().DS.'read_tpl_params.php');

Get the parameter:
  $some_param_val  = JAddons::getTplParams()->get('some_param');