Info/resources for building new server distro?

I want to build a (media) server distro based on OMV. All the "build your own distro toolkits" seem to focus on building a desktop distro. Can someone please point me toward info/resources that document how to add packages, configurable data, and customize the installer to ask the user for additional info during the initial installation?

For anyone who wants to get involved:, the future home of the repo is at https://github.com/DigitalLifestyleC...s/bazinga-box/