this is exactly what you need. The option "Decision can be made using stamps" enables stamps for this workflow task. The stamp has no extra configuration, it displays the same fields as the form/dialog box.
The only thing you can configure is which fields are actually stamped onto the document. This setting was introduced in 7.2.
Hope this helps.
Greetings from Germany,
Simon H. Hellmann
DocuWare System Consultant