You can download the JBoss version of your choice in the zip or tar format. JBoss provides startup scripts for many distributions and you can customize those scripts and add one of them to the startup scripts. On Redhat based distributions startup scripts are located in /etc/rc.d/init.d if I recall.
If you're familiar with JBoss, then you know that after unzipping the JBoss archive, launch scripts will be available in the bin directory.
If you're not new to JBoss and Java then I guess that you know how to deploy a Java application on JBoss. If not, follow the JBoss documentation.