I spent several days trying in vain to program my Colorduino using my Mega2560.
None of the tutorials that I found seemed to work for me.
This is what I came up with that worked right away:
Mega2560 Colorduino
RX0 (pin 0) ->> RXD
TX0 (pin 1) ->> TXD
RESET ->> DTR
5V ->> VDD
GND ->> GND
Mega2560
Reset -> 4.7uF capacitor -> 5V
When I uploaded the sketch, as soon as the size of the sketch appeared in the window, I held down the RESET switch on the Mega2560 until the upload completed.
I am now happily able to program my Colorduino using my Mega2560.