In the Gentoo-style, this is composed of a couple of items:
This example assumes that the SlimServer software is installed in /usr/local/slimserver, and that a user called 'slim' has been created to own the server software, configuration files etc. There's a section near the top of the init.d script that has some settings you may want to change for your local installation.
This example also runs the SlimServer nice'd to - 10 to give it extra priority - this is useful to minimise stalls in playback if you have a low-powered or busy server. Again, this is a configurable value near the top of the init.d file, which you can change if you like (zero will leave the server running at the default priority).
This startup script will work for at least the 5.4 and 6.0 branches of SlimServer.