Yes, you are correct.
You might, however, want to take a look at the service.bat that is included with the source code for JBoss in Action (http://www.manning.com/jamae). In ch15, if you run Ant with target 04, it generates two service.bat files to run two app server instances. If you look at the source for those service.bat files (ch15/src/service/windows/service.bat) you will see that the all of the necessary configuration information appears in env vars set at the start of the script. They are initally set to proiperty strings (that is ${...}) and the Ant build script replaces those with build properties.