As leon_ mentioned, you can just use the designer.war file in your app. The editor lets you create .bpmn2 files by draging and dropping components from a pallete.
If you follow this approach, you will need to handle the persistence of your processes.
If you are already using guvnor, and you want to embedd its editor in your application letting guvnor to handle persistence, versioning and distribution, you can use this new feature present in Drools 5.2: http://ilesteban.wordpress.com/2010/11/23/guvnor-embed-assets-editor-in-your-application/
You can get more information here: http://surdilovic.wordpress.com/2011/04/06/integrate-oryx-designer-and-guvnor-in-your-own-applications/