I have had GPO4 since forever, but only last night found a FAQ how to use Finale Printmusic together with GPO4. After installing the files as indicated, I setup another string orchestra score, switching the playback device from the softsyth to the GPO4 libraries in the setup screen.
It actually didn't do anything, but after I removed the original instruments in the setup page and replaced them with the proper GPO4 instruments from the list e.g. KS Violins 1 (keyswitched violins 1) they worked right off the bat.
I only tried simple stuff like staccatos and legato lines, and they seemed to work. Good stuff, as I was really jealous of my teacher's fantastic sounding samples in Sibelius XD Not that GPO brings it up to that level, but at least now I have at least _some_ kind of sampled orchestra with individual patches not a generic "string ensemble" patch to be used for all the string sections.