That's the same thing as what shreks pointed out at the bottom of his post.
AFAIK, that's the only plugin that has been written for a default Sharp player. In what way does it not work for the SL-3000's default player?
Do the files not show up? That may be a mime type problem. You need to make sure that one of the mime.types listed in the .desktop file for the default player under /home/QtPalmtop/apps matches (can include wildcards) the mime type for the ogg extension in /home/QtPalmtop/etc/mime.types .
P.S.
ELSI is the new ZSI.