If you are talking about the Evaluation process in the jBPM samples, that process was created manually (outside of Designer). It is pretty simple to create forms on your own if you wish. Just need basic understanding of html and freemarker. Process and usertask forms generated by the Designer are stored in Guvnor, in the same package where your process resides in. After generation Designer brings up a page where you can view their source, or you can view your package assets as well to find them there and view the sources (and change them if needed as well).
Hope this helps.