OK it's not that hard. It took maybe 3 hours for me to get this stage from nothing, i.e. downloading processing, looking at the examples, trying code, writing the complimentary arduino code.
import processing.serial.*; // Import the serial communication package
Serial port; // This came from all the example sketches
void setup()
{
println(Serial.list()); // What serial ports are avaialble?
port = new Serial(this, Serial.list()[0], 9600); // 0 = RS-232, 4 = USB
port.write(hour()); //Send the hours as a two digit number
delay(100);
port.write(minute()); //Send the minutes as a two digit number
delay(100);
port.write(second()); //Send the seconds as a two digit number
}
void draw()
{
// I just needed to send the time once, didn't need to do anything after that so draw() is empty
}
You'll need to change a few things - you'll want to move the port.write calls to the draw() function for example.
It should have everything you need to send stuff to arduino from processing though. You can get all of this stuff from the Serial Library page Serial / Libraries / Processing.org and the example is on the serial.write page write() / Libraries / Processing.org
You'll probably also want to use the keyTyped() function
void keyTyped() {
println("typed " + int(key) + " " + keyCode);
}