Index: class.t3lib_div.php
===================================================================
--- class.t3lib_div.php	(revision 3674)
+++ class.t3lib_div.php	(working copy)
@@ -4339,6 +4339,40 @@
 	}
 
 	/**
+	 * 
+	 * 
+	 * @param string $path = file absolute path (use __FILE__ magick constant)
+	 * @access public
+	 * @return void
+	 */
+	public static function XCLASS($path) {
+		global $TYPO3_CONF_VARS;
+
+		$xclassKey = false;
+		$pathes = array(
+			PATH_t3lib            => 't3lib/',
+			PATH_tslib            => 't3lib/',
+			PATH_typo3conf.'ext/' => 'ext/',
+			PATH_typo3.'ext/'     => 'ext/',
+			PATH_typo3.'sysext/'  => 'ext/',
+			PATH_typo3            => 'typo3/',
+		);
+
+		foreach ($pathes as $pattern => $prefix) {
+			if (t3lib_div::isFirstPartOfStr($path, $pattern)) {
+				$xclassKey = $prefix . substr($path, 0, strlen($pattern));
+				break;
+			}
+		}
+
+		if ($xclassKey && defined('TYPO3_MODE')
+			&& isset($TYPO3_CONF_VARS[TYPO3_MODE]['XCLASS'][$xclassKey])
+			&& $TYPO3_CONF_VARS[TYPO3_MODE]['XCLASS'][$xclassKey]) {
+			t3lib_div::requireOnce($TYPO3_CONF_VARS[TYPO3_MODE]['XCLASS'][$xclassKey]);
+		}
+	}
+
+	/**
 	 * Simple substitute for the PHP function mail() which allows you to specify encoding and character set
 	 * The fifth parameter ($encoding) will allow you to specify 'base64' encryption for the output (set $encoding=base64)
 	 * Further the output has the charset set to ISO-8859-1 by default.