Internally the params are stored in $this->request->params['paging'][$model]
, where $model is the name of the desired model. The exact data in this variable can be found in the Cake docs. You will always need a name of a model, but you can make one up.
In your controller:
$this->request->params['paging']['MyModel'] = array(
'pageCount' => 3
);
In your view:
$this->Paginator->param('pageCount', 'MyModel');