The installer sets up LMS in pretty much the same way as the FreeBSD port. 

Most of the application resides in a version-specific directory in /usr/local.
The symbolic link /usr/local/squeezeboxserver is set to point at whichever
version you've installed. The data is stashed in /var/db/squeezeboxserver,
and the logs are in /var/log/squeezeboxserver. These are links from the main 
directory, set during installation. During a fresh installation, the rc script 
/usr/local/etc/rc.d/squeezeboxserver is installed.

If the installer sees the link /usr/local/squeezeboxserver is already there,
it will do an upgrade. Old versions are left around, but the link is set to
point at the latest version. The log and db links are recreated but the dirs
are not touched. You may want to keep copies of the cache dir.

So: Run the script install.sh, as root, from the current directory. Example:

    # cd <your-directory>
    # ls
    INSTALL
    README
    install.sh
    logitechmediaserver-7.7.3-33978-perl-5.12.4-FreeBSD-8.3-STABLE-amd64.tgz
    logitechmediaserver-7.7.3-33978-perl-5.12.4-FreeBSD-8.3-STABLE-i386.tgz
    [... maybe other stuff ...]
    squeezeboxserver.tpl
    # sh install.sh

You can stash several versions. If only one version is available for your OS
and architecture it will be used; if there is more than one suitable version 
you will be asked to choose. No matching versions: bomb. But you can specify:

    # sh install.sh logitechmediaserver-blah-blah.tgz

e.g. 8.X under 9.X mit compat. Do try to install a version which will run.

During a fresh install, the rc file is generated from squeezeboxserver.tpl.
The script will also copy in your server.prefs file if it sees one. 

FWIW install.sh is what I use for one-command installation and upgrade, with
bells and whistles added. Sorry, but there's no cute animation of a demon 
poohing on a penguin.

This little project was an Act Of Unpatriotic Olympic Avoidance.

Um, enjoy, or something.