Codes linked to Hotel Hideaway game have been added to Habbo Hotel. From Settings, in your Habbo account, you will see a tab written "Hideaway". By clicking on it, you will access a page with a QR Code, possibly an invitation or access pass to the Hideaway.
(The page has some bugs)
At the moment, this page is accessible only from an ultra-secret hotel, restricted to only a few Sulake Staffs, but the links will be: