I just hooked the DICE up without its case and made some measurements and to confirm I had the right pins.

Yep it all looks good - Ive updated the image with markings for the pick up points for the blinkers and the power supply.

Ill hopefully get a chance later today to solder the Arduino in and give it a go.

The multiplexer (74HC151) second from the left is the chip we need to attach to.

Pin 1 Left blinker input

Pin 2 Right blinker input

Pin 16 +5V

Pin 8 0V