🤔Hmmm...
You've been a member since 2007, you have all of the VSL collections and you're not sure how to go about making a mockup?
Don't get me wrong, I'm not trying to be condescending I'm just wondering what you've been doing with your libraries all this time if you're just now getting around to recording a mockup.
Anyway, I think in your case, write your score out in Finale then export to a MIDI file. I don't own DP8 but if it's like any other professional DAW I'm sure you can then import the MIDI file into your DAW and work from there.
Again I don't own DP8 but I would just remain working within that environment unless it lacks some functionality that you need for your work flow. If you're filmscoring, Cubase and Nuendo I think are more suited for that because the audio to image sync'ing features are more intuitive. Then again, I don't use those programs either so maybe somebody else can chime in on that.