Accessing Rails generators from a Radiant app

I am just getting started on a new radiant site. I generated it via the
radiant shell command (v0.9.1 gem). I would like to use devise as the
authentication mechanism for the site. I came across a wiki page
how to do it:

The wiki page calls for following the devise instructions for gem
installation and then generator usage for creating a custom user model
(along with other instructions for setup). My problem is that I can’t
to access the devise_install generator (or any other generator that
included with radiant). When I run script/generate, I see:

Installed Generators
Builtin: extension, extension_controller, extension_mailer,
extension_migration, extension_model, instance, language_extension

None of either the Rails generators or generators provided by gems I
installed in my environment are visible to me. Is there some step I
need to
do to be able to see non-radiant generators?

Thanks in advance,