Basically, you need to build the USB-ST4 interface described in the github project page and modify your control pad like explained here if it doesn't have an ST4 port.
Modifying the control pad means soldering and wiring an RJ12 socket to the pad buttons.
Once the hardware is done, you will need to install the ASCOM platform and the driver.
After this you can use a software like the open source stellarium to play with your telescope or PHD for astrophotography.
More details are available on the github project page.
Sample video of the telescope moving:
Hey, this seems like a really cool project, so I wanted to make it for my Skywatcher Star Adventurer (2i). Unfortunately I was unable to find the TLP521-4 optocoupler, so I had to get the pc817 4 (on a green pcb) (the only one I could get in a reasonable amount of time). I didn't think much about it, but after trying it out it didn't seem to work. Does anyone know if that optocoupler should be usable (or if it's just me doing something wrong). The optocoupler does get the signal from the arduino (LEDs on it blink), and I was able to see a change in resistance when it was enabled, but the Star Adventurer didn't get any signal (the LEDs weren't blinking). Is there a way to test if it might just be the mount's st4 port that is broken (like connecting the wires by hand maybe)? Thanks in advance, Sam