Copy Doctrine.php and Doctrine folder to library folder.
Now add following function to your Bootstrap.php file.
public function _initDoctrine(){
        require_once 'Doctrine.php';
        $autoloader = Zend_Loader_Autoloader::getInstance();
        $autoloader->pushAutoloader(array('Doctrine','autoload'));
        $manager = Doctrine_Manager::getInstance();
        $options = $this->getOptions(); // zf application config array
        $dsn = $options['dsn'];
        $conn = Doctrine_Manager::connection($dsn, 'defaultConn');
        Doctrine_Core::generateModelsFromDb(APPLICATION_PATH.'/models',
                array('defaultConn'),
                array(
                    'generateBaseClasses' => true,
                    'generateTableClasses'=> true,
                    'classPrefix'=>'Model_',
                    'classPrefixFiles'=> false,
                    'baseClassesDirectory'=> '.'
                    )
                );
}
The above code creates your Doctrine connection, so else where in your code you can use $conn = Doctrine_Manager::connection($dsn, ‘defaultConn’); to get a connections to database.
Also the above code gets DSN setting for you database which looks like dsn = “mysql://username:password@host/database_name” in your application.ini file.
The function Doctrine_Core::generateModelsFromDb with above settings will generate table and record classes for all the tables in your database and would save them to your application/models folder.
As all the classes generated by Doctrine would be prefixed with “Model_” you can would be able to use them anywhere in your Zend framework application because of ZF autoloader. As the above generated class would follow ZF convention for models.