Don't forget that my program HARMONY can do tablature for Melodeon, Anglo concertina, and similar instruments, and can be adjusted for different tunings (My early Erica doesn't have the accidentals on the lowest buttons, for example).

There is an option to give precedence to the direction of the bellows, which is good for showing how to play across the rows.

(The other option is to give precedence to the home row of the key)

You can also use it for picking out chords. Just make up a little tune with the notes of the chord you want, and it will show you all the buttons.

Download here