I too am working on archiving as a backburner project. After archiving the archived Wf log was available from the GOS-Workflow-Archived Workflows menu. This passes the Object reference to the reader program, the same reader program thats available from SWW_SARA.
The reader program then presents a popup presenting the Sessions and Files available to search. I selected the Session I knew the document was archived into and after a bit of a wait (quite long) it presented the Wf log
I did not specify a Filepath to the archive when/for reading. I believe it is making a link from the Archiving Object 'WORKITEM' to the Logical Filepath (table ADMI_FILES might have something to do with it) Debug program RSWWARCP