either this forum or the arduino one is the only 2 i have seen talk of rainbowduinos.
you could try going the mega-isp route if you have an arduino laying around. thats how i get mine programmed. and once i have that, i use avrdude manually. there is also an avrdude gui but in previous posts i put what commands i used to copy it over.
you have 4, but you are trying to program them individually? are you putting custom “images” on them? you could control them with the i2c method plugged into one and the use the address function in all the drawing methods, to control which one you are writing to.
the reason it wasnt working initially on mine was because of the speed that avrdude was trying to write to the chip. when i manually specify the speed, it works just fine. i dont have an actual isp programmer so i dont know if it was just the sketch i used (mega-isp) has it set to some value, or if the m168’s require a specific speed.