Nope files where never stored in userid directories. They have always been in numeric categories to my knowledge. I beleive they where stored in a data directory with no cat id back in the perl version but in the upgrade 2.52 script the new category directories are created in data but again this happened when php version of Photopost came out. Thus a file link would have been in the perl version
http://www.domain.com/photopost/data/useridimage.jpg
No workaround that I am aware of or can think of for you.