It would be the DIO3 pin, but you have to bridge it to the RTS pin. You can set the settings in the com port options in windows so that the RTS pin will close when you start transmitting, making the board reset, ready for programming.
Follow that guide slowly and carefully, I've had a proper read through it now and it looks pretty comprehensive to me
All the electronics to get it going are there for sure.
It would be pin 16 and 17 on this example board http://www.robotshop.com/content/images/droids-bluetooth-layout.jpg
. This board has the same pin layout even though it's a bluetooth board)..