Jick Duck, I am not certain how you intend to use your Trumpet VST. You can setup forte such that it changes Scenes in reponse to program change commands. You would need to setup the appropriate channels as well and save the Scenes. If it takes more than 10 ms to load your VST then you would get a break/hiccup in your OMB Style playing.

Another alternative would be to acquire a suitable trumpet in soundfont and add it or change it in your soundfont wavetable.