The technique I use is to first establish the base note for the left hand, which is usually a relatively low "A" note that is constantly held.
Next, play the melody with your right hand, using a Floyd Kramer type of fingering. I don't have my keyboard here at home right now, but if you listen to 254 in the attached midi you'll get the idea of how I do it.
https://app.box.com/s/t6neciwv2k8iskswjtu2pw238r4x0nd8 Gary
You might want to consider creating a drumset containing a single sample with the bassnote/buzz generated by pressing the bagpipes..and then using a multipad to generate it,,,
This gives your left hand the freedom to play chords,, or/and an other part,,,