Redmine

Hello, I am trying to create my plugin to utilize the acts_as_event/activity plugins.
I have everything working except for the url option.

belongs_to :project
acts_as_event :title => Proc.new {|o| "#{o.title}"},
              :author => nil,
              :datetime => :updated_on,
              :description => Proc.new {|o| "#{o.description}"},
              :url => "http://yahoo.com" 
acts_as_activity_provider :timestamp => "#{table_name}.updated_on",
                          :find_options => {:include => :project,
                                            :select => "#{HflEvent.table_name}.*"}

What I want to do is just link to an outside website instead of the show method. As you can see, I'm just trying to link to yahoo, but it interprets that as a method called "http://yahoo.com". Anyone know of a way to get around this without having to hack the redmine internals?