Многократно подчеркивалось, что компонент alpharegistration работает со стандартным модулем авторизации joomla:
With AlphaRegistration, improve your Joomla! register form and secure it with reCaptcha system and BotScout service. With AlphaRegistration, you can displaying an image for each step of registering user and add a check box to accept terms of use of your website. Install the component, then, check settings and that's all.
No need install a new module for login. AlphaRegistration works with the login module of Joomla! (No need to create a menu linked to this component).
Скажите, а вы пробовали редактировать стандартную форму авторизации? вот
так или
так.
