Using CD74HC4067 multiplexer with drumkit-kit (spikenzielabs) code

Using Arduino Programming Questions
2

See these pages:-
http://www.arduino.cc/playground/Learning/4051

http://www.thebox.myzen.co.uk/Hardware/MIDI_Footsteps.html

I have no idea what half of this code means

Time to start learning then. Extending what other people do is a good way to learn but you need to put in a bit of effort.
Basically you need to make the arrays bigger to take account of the greater number of inputs. Then you need to read those in by:-

  1. Setting the multiplexer select lines to the value of the input you want to read.
  2. Reading the value switched in.