JMiniX is primarily designed to be embedded in an existing application, that's precisely what it makes it different from other JMX consoles.
However, nothing prevents you to make your own war containing only JMiniX. You just have to create a new J2EE web project, add the JMiniX library and configure the web.xml according to the documentation. To bootstrap your web project, I suggest that you use the Maven plugin for Eclipse. It helps you create it in a few click. There are plenty on tutorial/docs to create a web project with Eclipse/Maven on the web.