Using multiple JVM combinations

http://livedocs.adobe.com/jrun/4/JRun_Service_Pack_1_Guide/4relnotes7.htm
You can use more than one set of JVM configuration properties for the JRun servers in a JRun installation. This feature is documented in Installing JRun, and is available from the command line and when running JRun as a Windows service.

For the following procedures, you can put the custom configuration file in the jrun_root/bin directory, or you can specify a complete path to the file.

To set up and use a custom JVM configuration from the command line:
Copy the jrun_root/bin/jvm.config file to a new filename.
Modify the new .config file to meet your needs.
At a command prompt or shell, start a JRun server using the following command:
jrun -config custom_jvm.config -start jrun_server

where custom_jvm.config is the name of your JVM configuration file, and jrun_server is the name of your JRun server. You can specify one or more server names separated by commas.

To use a custom JVM configuration when starting JRun as a Windows service:
Install the service using the following command:
jrunsvc -install jrun_server service-name service-display service-description
-config custom_jvm.config