There are two ways to operate Musicextras from inside Prokyon3:
Single track scan: You can initiate a Musicextras search for a single track by selecting the track in the central track list and by hitting the "WWW Scan" button on the "Extras" tab in the right pane.
Complete collection scan: You can initiate a scan of your complete music collection by selecting the "Scan all" action from the Musicextras dropdown menu.