I did something similar - where you usually see the "perhaps you forgot to login" message, I wanted to prompt the user to log in instead of showing them that message.
In actions.php, look for the line
And replace it with
This just makes the user sent to the login page rather than the page telling them they need to go to the login page. To be friendly I also added a message on the line before:
msg('You must log in to view this page',-1);
Hope that helps someone.