You can download the ZIP database manager from the Roland site of Italy; here is the link: http://www.roland.it/download_arranger.htm

beware: the file exceeds 6 Mb in size.
The ZIP database doesn't "see" automatically a style file, even if the style is phisically present on the ZIP disk; the only way to make it "see" it is to save the file from a floppy disk into the ZIP disk (this way the keyboard adds the style to its database).
Even using the ZIP data base manager, however, you cannot import styles from the hard disk (the import function works only for songs or midifiles, which have a separate database).
This is really annoying; I am going to try another way and see if it works: I will try to create a new database for styles, import again all the styles from the ZIP disk and then rename a few styles to match the name of the style present on the ZIP disk (but not acknowledged by the ZIP data base); the name that really matters is the last one (in the right column, because this is the identifying name of the file).
The final step is to merge the renamed styles
into the original style database.
(All this can sound a bit confusing maybe, but once you have the program installed on the computer you will understand).
Regards,
Andrea