wpforo independent login form

I have installed the wpforo plugin. This is the core of the site. wpforo has a login ability but this includes the forum being partly visible to geusts who are not registered yet. The plugin “user registration” allows to register without using wpforo so wpforo can remain hidden. Now the probleem is login: How can I allow registered users to use a login form avoiding wpforo? Is a plugin available to provide login not using the wpforo-login?

The page I need help with: [log in to see the link]