and here you can find schematics both from the whole board, and from the led driver chip itself:
http://iteadstudio.com/produce/colorduino-schematic-and-demo-code/
How is this for you? I only get a PDF file with squares and lines on it. No part numbers, no pin numbers, no IC signal names. It could be the schematic for anything. I am running a Mac so it might be an odd sort of Widows PDF.
as there is no common ground, but both ground and positive are switched on and off by the controller
Yes that is how a matrix works. See my page:-
http://www.thebox.myzen.co.uk/Workshop/LED_Matrix.html
Maybe something with NPN transistor on the 8 Vcc pin(LED's common anode), and PNP transistor for the 24 RGB pin?
It is not as simple as that because you need something to limit the current through the LED. A resistor will not cut it for a 1W LED because the forward voltage drop of these is not stable. Therefore you need something like a constant current supply to limit the current as well as hefty drivers. FETs will be better than transistors at these values.