Hello @scanner_darkly!
Welcome to the forum 
There aren’t still any instructions for this, but I’ll give you a quick guide.
First of all you’ll need the Arduino IDE to compile, or the Visual Studio Code with the Arduino environment set-up.
In our Gitlab repository you will find the libraries and hardware-def folders (rename hardware-def to hardware). Both need to be placed inside your Documents/Arduino folder.
Then open the IDE and go to Tools -> Board -> Board Manager, and install the
Arduino SAMD boards package.
After this download the ytx-controller folder from our repo containing the controller’s code and open it with the IDE.
You can tweak or add whatever you want. Make sure you don’t add too much overhead to the controller’s loop time so the hardware scanning doesn’t degrade too much.
If you open the serial monitor, and press send the letter ‘t’ at 250.000 bps you can enter test mode and with the ‘m’ command you can print loop time.
To compile the firmware, go to Tools -> Board and always select Yaeltex Kilomux and not the Yaeltex Kilomux (test) version.
Then go to Sketch -> Export compiled binary and if the compiling succeeds, you will see the binary file inside the ytx-controller folder.
To upload the firmware, check this guide: How to update firmware for v2 controllers using the desktop loader
This should get you all set to start building and uploading firmware!
If you have any doubts or ideas you’d like to share about specific feature implementation, we’ll be glad to see them on this forum 