Advice on implementing security

[Quinton McCombs]

I need to secure some of my screens.  Before allowing the user to access
a particular screen, I will check to make sure that the user has the
appropriate permission.  If they do not, I want to send them to
different screen to display a friendly message about not having the
appropriate security.  I already understand how to change the screen
template in an actions.  The question is how do I do this if I am not
calling an action?