This space isn't meant for these kind of questions, it is only for the NWSSO product. The correct space for your question is either SAP NetWeaver Portal: Application Integration or Web Dynpro ABAP depending on what the focus of your question is.
Anyway, no you can't do it with WDA since the existing WDA portal integration API doesn't provide access to the portal system landscape. With OBN navigation you have to know the system object.