AntInstaller

Did you considered switching to Maven 2? :)

In our internal project we considered using antinstaller and to do so I've
refactored sources for Maven 2, so it better fit our build process. In my
own opinion, the sources look better and build process became more simple
and straightforward. You can take a look of new source structure I've got
here: http://wfrag.org/files/antinstall-mavensrc.tar.gz . It lacks several
things (web site, some image and all unittest directory), but these sources
are enough to build an installer for demo application (mvn install from the
sources root directory, the demo installer will appear in
antinstall-demo/target/antinstaller-demo-0.1.0-SNAPSHOT-installer.jar).

Answer to the initial question. In fact, you do not need a plugin to build
installer, you can use maven assembly plug-in to prepare required installer
.jar. You can look for the example here:
http://wfrag.org/files/antinstall-mavensrc.tar.gz (look how antinstall-demo
is build). Of course, it assumes that installer .jars are in Maven
repository, but probably you could update assembly descriptor so it takes
required archives/files from predefined directory (where antinstaller is
installerd).

We dont use maven 1 or 2 to build so if anyone fancies knocking up a
plugin please feel free.

However try to make sure that the plugin creates an editable set of files
not a single Jar, since it is likely that at least the
antinstall-config.xml and build.xml will need to be customised