EJB / EE :: Custom Authentication Provider - How To Execute

In spring there is a Custom Authentication Provider, my question is from a jsf login page how can I execute this provider ?

@Component
public class CustomAuthenticationProvider implements AuthenticationProvider {

@Autowired
private UserService userService;

@Override
public Authentication authenticate(Authentication authentication) throws AuthenticationException {
String username = authentication.getName();
String password = (String) authentication.getCredentials();

[Code] ....