GUI login banner at console?

[Scott R. Ehrlich]

I've just installed 7.10 64-bit on a workstation and want to produce a 
multi-line text banner with an acknowledgement button (OK/Yes/whatever) on 
the console before the username/password prompt appears.

Under CentOS or Fedora, I would place /usr/bin/gdialog --yesno "This is my 
long intro banner..." in /etc/X11/Xsession just after the first batch of 
comment lines.

What would be the equivalent way for Ubuntu Gutsy?

Thanks.

Scott