I need help creating a warning banner of custom text when someone is about
to log into the console, ideally before they enter their user/pass, but,
if needed, it could be after.

This is NOT for a remote login, but the graphical console screen.

I happen to be using 64-bit Gutsy.

I tried gdmsetup, and selecting Custom under its Local tab, then typed in
some random text, but saw nothing even on reboot.

Funny thing is, an out-of-box install permitted gdmsetup to work fine. But
after an apt-get update/apt-get upgrade, gdmsetup core dumped after
attempting the custom option.

So what do I need to change, and where?

Under CentOS/Fedora, I can easily place /etc/gdm/kdialog --yesno "This is
my custom banner" as the first uncommented line in
/etc/X11/xinit/Xsession, but that doesn't seem to work in Ubuntu.

Thanks for any leads.