Return Custom Error Page from Realm

[Anderson, M. Paul]

I've created a derived realm that performs a custom authentication scheme.  I'd like 
to be return a custom error page when the user has attempted to login to the system > 
3 times and failed.  The user will be locked out until a sys admin allows them back 
in.  Since I'm obviously doing the authentication in the Realm I'd also like to return 
the error page from the realm.  Is there a way to do this?
 
Thanks!