OK, I managed to sort this out myself, hopefully this will help some else, time to build the circuit and test.
I had to modify the Adafruit_NeoPixel.h file to clear the "undefined NEO_KHZ400" error, I commented out lines 101 and 103,
#define NEO_KHZ400 0x0100 // 400 KHz datastream
plus I also created an i2c Neopixel library in the user's Arduino library folder and copied the i2c_neopixels.h file to it.
with the above changes the code should now compile.