If you have some decent Virtual Instruments you can use RapidComposerLE or full version to create some great UserTracks.

1. Load a UserTrack Template, most are on here http://www.realband.org/tutorials.html

2. Open an SGU template in BB

3. In Prefs > Output Chords set Enable, Complex Chords, write track to midi file

4. Save As MID > File on disk

5. RapidComposer > Import Midi > Select BB Chord Output track

6. Mute the Chord Track and Add Track

RapidComposer will fit any midi anywhere to chord/scale.
You can drag any Midi Generators in from the Phrases window
or your own midi files/loops from a folder.
You can now split the midi where you like, right click Convert to Relative form and save it as a custom phrase to the Phrase window.
Right click Phrase Generators in the track for more options.
Click the little button after M S "=" on the track to color note by Chord/Scale/Out.. you can switch to Edit mode or double click to enter the Phrase Editor, in there set View to Chord/Scale/Out.. click Apply Changes then exit.
You can create "Key Switches" for you Virtual Instrument articulations, these are left in Absolute mode so they don't change note as you move them across the chord track, save them with the same name as the Phrase they belong with 'My Riff 004' 'My Riff sw 004' so My Riff 004 might have a slide or bend switch that goes with it.

7. Export As WAV for both Mac and Win

8. Open the SGU Template in BB, set it to the tempo of the usertrack

9. File > Import Audio wav (from RapidComposer)

10. Save As UserTrack

If you have RealBand it is easier in that.

http://www.musicdevelopments.com/editions.html