Make up a lead from 6 x 0.1" header to 6 flying leads. I used a colour ribbon cable: black/brown/red/orange/yellow/green (which matches the FTDI colouring and STII board marking).
I took an Arduino Uno (you could use any Arduino with a socketed CPU), removed the CPU from its socket (the solder time will be the CPU now) and connected the flying leads to the Arduino as follows:
- Pin 1 (Black) to 'GND'
- Pins 2,3 not connected
- Pin 4 (Orange) to 'RX'
- Pin 5 (Yellow) to 'TX'
- Pin 6 (Green) to 'RESET'
Hold the header side against the Solder Time II programming pins at an angle. Pin 1 (black) aligns with the 'BK' marking on the PCB.
Plug the Arduino in, and you can program the watch straight from the Arduino IDE as usual (set the IDE as per the Solder Time II instructions). You can also watch progress on the Arduino TX and RX LEDs.