When first setting up the site, you run slash/bin/install-slashsite script which lists the plugins and asks you which one you want to use.
There is a script in slash/bin to just install a new plugin.
HOWTO-plugins from Slash docs
NAME HOWTO-Plugins - How to write and use Slash plugins QUESTIONS What is a plugin? A plugin is an extension to the Slash system that adds some sort of functionality to the site. It should inherit its basic look and feel from the currently running theme (for example, background/foreground colors, calling header and footer components, etc. will be handled by the installed theme). How do I get my plugin into the install system? There are two ways to do this. First, you can put it in the plugins directory with the distribution. During the install it will be copied to the plugins directory in (by default, /usr/local/slash/plugins/. The second option is to copy it in there yourself and make sure that your library files (perl modules) are installed. If you decide to go the first route you may want to consider adding your libraries to the list of plugins that get installed, in the main Slash Makefile. What does my plugin need to make it work with the install? If you look at the plugins that come with Slash you will find a file called PLUGIN. This handles how the plugin installer will see your plugin. In the file, each keyword appears on a line by itself with a '=' seperating it and the directive. For example: htdoc=search.pl The following are the keywords it knows: description What will be displayed during the install for the user, describing what the plugin does mysql_schema Schema for MySQL mysql_dump Dump for MySQL pg_schema Schema for PostgreSQL pg_dump Dump for PostgreSQL htdoc A document to be installed in the htdocs directory for the Slash site template A template to be installed in the database image An image to be installed in the image directory note A note to show the user when the install is over. Good place to put notes about aditional libraries needed, or other dependencies. How do I install a plugin once my site is installed? Use the install-plugin tool. If run with the "-h" option, it will describe the tool's usage. If can list available plugins and you can then select which plugins you want to install (just like with install-slashsite). Do install-plugin and install-slashsite use the same logic? Yes, you can find it in the Slash::Install library. I have a really cool plugin and I would like to see it added to the Slash distribution. Wi ll you distribute mine? Maybe. We don't have any rules concerning this at the moment, so it will be on a case by case basis. At some point in the future we will come up with a much better answer.