how to install validates_multiparameter_assignments plugin?

Hi,

I'm trying to install the validates_multiparameter_assignments
plugin. I don't see any installation instructions on
http://agilewebdevelopment.com/plugins/validates_multiparameter_assignments,
where the zip is located and when I try

[me@machine]~/w/easyrx% script/plugin source
http://www.kbmj.com/~shinya/rails/validates_multiparameter_assignments-1.0.zip
Added 1 repositories.
[me@mymachine]~/w/easyrx% script/plugin install
validates_multiparameter_assignments
Plugin not found: ["validates_multiparameter_assignments"]

I get the error message above. Thanks for any clarifications, - Dave