[ddouglass]

No program is going to be able edit the songs database file except for Hoster itself. To use any of the file renamers you will need to remove the songs from the database, rename the files without the underlines, then re-import them.
There is no way around this unless you want to keep editing them one at a time in Hoster.
The songs database is not the only thing needs to be changed. Each file has a header in it with this information too. So even if you could open and make changes in the database it would not completely solve the problems.
It really is not as difficult as you think it is. Just search in the edit by bookid or diskid using the multiple search and delete those from the database, then do the renaming and re-import again. The importing for MP3 is very quick.