There is a complicated way to apply other vst instruments in finale:
- take a piece you wrote
- go to midi/audio > device settings > vst plugin management > add the folder in which you have the .dll plugin
- go to midi/audio > instruments settings > here you can change the instruments realating to midi channels. If you click on the pen symbol you can interact with the plugin to manage the sound.
you can find free vst at : http://www.vst4free.com/ , but there are other sites too.
I´m not 100% sure this will work for you however, since I´ve another version of finale.
I´m looking for a way to integrate those instruments in the setup wizard, if I discover a way I let you know.