This module is developed as part of YaST. See the development documentation.
Have a look to the AutoYaST Development Documentation if you would like to implement AutoYaST support for your YaST module.
To get the source code, clone the GitHub repository:
$ git clone https://github.com/yast/yast-autoinstallation.git
If you want to contribute into the project you can fork the repository and clone your fork.
There are several possibilities how test an updated code. It also depends on the fact in which stage of installation it comes into effect. First stage runs between the start from installation media to reboot (or kexec), then continues second stage.
Either use StartShell=1 option in Linuxrc, edit the installation system and run yast manually or use a DriverUpdate via Linuxrc.
There are two possible ways how to rerun this stage, just keep in mind that the system might be already configured and thus it might behave a bit differently:
cp /var/lib/YaST2/install.inf /etc/
touch /var/lib/YaST2/runme_at_boot
cp /var/adm/autoinstall/cache/installedSystem.xml \
/var/lib/autoinstall/autoconf/autoconf.xml
reboot
or faster without rebooting but with possible side-effects:
yast ayast_setup setup filename=/var/adm/autoinstall/cache/installedSystem.xml
If you have any question, feel free to ask at the development mailing list or at the #yast IRC channel on freenode.