It's one of the things where, if you don't know how to approach it, you probably don't want to be doing it (because it'll cost you too much time). It's not inside the "normal" use case of a netduino - you'd need to take the source of the firmware, add the required functionality there, compile it and overwrite the firmware on your netduino with your custom one.
hi stefan,
I left I2C and now trying trying to connect 2 netduino to one netduino using RS232 as it has two serial port pins.....Anyway thanks for your reply.....