How to install ActiveScaffold plugin?

I am upgrading to raills 2.3.2. I’m having problems with AjaxScaffold
which has been deprecated.
I am a linux novice. The web site http://activescaffold.com/ has the
following command:
script/plugin install git://github.com/activescaffold/active_scaffold.git
I tried the above and also ruby script/plugin …
Nothing happens.

Any ideas?

Do you have git installed?