Hum I guess that the easiest way is to use an electrolytic cell, http://en.wikipedia.org/wiki/Electrolytic_cell and put graphite (the black thing inside your pencile) to both electrodes... Put an acid solution water and ammoniac will be fine...

I am trying right now... The water is getting less limpid and gasses (I guess O2 and H2) are coming out. I am using a 9 Volts battery.