GUI login banner at console?

[Scott R. Ehrlich]

The first round didn't yield answers that worked, so I'm trying again.
There _must_ be a workable answer...

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