edit patterns for studio instruments.

What host software are you using?
 
In Sonar it would be easy to insert SI and assign a midi track to SI. I don't think you can add you oen paterns to SI but in Sonar you could ues the media browser to audition existing MIDI loops. Or you can ceate your own loops in the step sequencer.

hello?

sw,
In MC4, click the ALL tab at the bottom left of the track view. This will make all of your track parameters available.
You will probably need to drag the bottom of your MIDI track down to see them.
Once your outputs are exposed, you can assign the output of any MIDI track to any synth you have inserted in your project.
You can't add your patterns to the SI library, but you can create them in the Piano Roll view(or Staff View if you prefer).
You can create patterns up to 256 beats(64 measure in 4/4 time) and convert those to Groove Clips if you want to loop them.
See the Help files on MIDI Groove Clips for more details.