PM sent.
Thank you.
Verlag Der Speilleute has a few books that you could use, these two are probably closest:
http://www.spielleute.de/product_info.php?info=p74_die-sackpfeifen-fibel---band-1.html
http://www.spielleute.de/product_info.php?info=p79_die-sackpfeifen-fibel---band-2.html
These are for the so-called “medieval” bagpipes (no historical background) which are open-fingered and give a dorian scale in A (and can be used for nothing else), based on the six-finger note.
Although these tunes can be played on the Hümmelchen if transposed to D dorian and the drones tuned to D and A, this is not what the Hümmelchen is designed for, and remains behind its actual possibilities.