In Prefs > Chord Output, Enable
Set the note range range to output
for using Kontakt Akkord Guitar use 34-60
for using Kontakt Strummed Acoustic 60-84
Go to Midi Button > Midi Drivers check Use VSTi/DXi Synth
Choose Kontakt, close window
Go to Plugins Button > VST/DXi Synth Settings to Edit the VSTi
Load Kontakt Instrument set Midi in Ch to 9 or same as in Chord Output settings or Omni.
This will play the same pattern that Akkord or Strummed Acoustic is set to.
To use key switches to change the strum patterns,
Click the MID button > File on Disk > Save the song.mid
In BB Prefs > Chord Output > Dissable
File Import > Melody from Midi file
Select ch 9 or what it was set to in Prefs > Chord Output
On the Melody track plugin load Kontakt Instrument set Midi in Ch to 9 or same as in Chord Output settings or Omni.
Click the Piano Roll Button to open the editor for the chord track
Hold Ctrl+Shift to add the key switch notes for Kontakt to change patterns.
Move notes up or down by dragging them, Delete key to Delete them or right click to cut copy paste.
Drag the left end of the note to move, right end to adjust length.
In the bottom pic the red note in the piano roll corresponds to the first red note on the Kontakt keyboard, that is the first pattern switch.
If you don't want to be bothered setting it up you can always make up some UserTracks with the Virtual Instruments, this way you will only have to choose a UserTrack just like you choose a RealTrack.
Just add an Ending key switches where the Endings are.
There are lots of UserTrack Templates http://www.realband.org/tutorials.html