A question about submitting parameters using Ajax.Updater

Hi, How can I use Ajax.Updater to send parameters from HTML - param1 and param2 the values of which are not in a form as such using Ajax.Updater in a manner such that on the server side, I use the model's update_attributes method.

new Ajax.Updater(       '#{options[:update_html_id]}',       '#{options[:update_url]}'+id,       {asynchronous:true, evalScripts:true, parameters:'authenticity_token=' + encodeURIComponent('Hl7TS7DG2dM0zmGAO09HMU8rKTNJwto37APahAPK9vA=') }       )

How can I modify the Updater above to generate the data below so that I can use model.udate_attributes(params[:some_model])

{ "authenticity_token"=>"Hl7TS7DG2dM0zmGAO09HMU8rKTNJwto37APahAPK9vA=", "some_model"=>{"param1"=>"value1", "param2"=>"value2"}, "id"=>"100"}