I'm really happy to hear that you are interested in adding these install packages. I did a fair bit of work on the daemon project a few months ago so I will try to give you a bit of info.
In a nutshell, the daemon plugin creates an install image using the CreateImageCommand class. Then each package type extends Target and MojoCommand, so for instance the rpm packager has RpmInstallerCommand and RpmTarget. The Target class gets configured from the pom.xml in the daemon plugin section and passes the props to the MojoCommand which then runs whatever commands necessary to create the package.
That is the most basic info, obviously there is more to it than that but hopefully that can get you started. There are also some places where the work was ongoing and needs to be cleaned up a bit since this framework has gone through several iterations to get where it is. Suggestions are welcome and if you want to help out and make improvements we are glad to work with you. As the number of platforms has expanded, the requirements and updates to the daemon framework has increased to make things more flexible so I would imagine the same will be true to add the packages you are mentioning.
If you have more specific questions feel free to post here or ask on IRC and I will try to help out.
The source code from daemon-plugin indicates that I might find answers
on this list. Does anyone know where I might find documentation (or
even mailing list discussion) that would augment the comments and
source code for daemon-plugin? I'm trying to scope effort required to
add Solaris pkg, HPUX depot, and AIX bff.
P.S In searching the archive, I notice that people often use
"[identifier]" prefixes in the subject when posting to
email@example.com. I suspect that this helps subscribers to
folder email properly (or to search the archive). If so, what are the
conventions for selecting the bracketed identifiers? For example:
should I have prefixed the subject of this post with [daemon-plugin]?