$commands[] = ajax_command_invoke(
  NULL,
  'mymodule_command',
  array($data)
);

$.fn.mymodule_command = function(data) {
  // dialog ajax id
  var dialogAjaxId = data.id;
  var blah = JSON.stringify(data.values);

$commands[] = array(
  'command' => 'mymodule_command',
  'arguments' => array(...),
);

Drupal.ajax.prototype.commands.mymodule_command = function(ajax, response, status) {
  console.log('mymodule_command', ajax, response, status);
  console.log('arguments', response.arguments);
};