You can try FemtoIDE, for example. That’s what I’m using.
Once you have that installed, just unzip the cyclometer code into FemtoIDE/projects/Cyclometer folder, start FemtoIDE and choose Cyclometer project from the list.
Here’s the modified design. The axles don’t go through the Pokitto connectors as easily as you’d think though. Fitting is really tight and I think the bush parts at top of axles are not actually needed. I haven’t done any field tests yet because of this exceptionally warm and wet winter/prolonged autumn, but the design feels secure and removing Pokitto is slightly easier and smoother than with the pegs.