You might need the following options for java during startup:
"-Dcom.sun.management.jmxremote",
"-Dcom.sun.management.jmxremote.port=5000",
"-Djava.rmi.server.hostname=<server-hostname>",
"-Dcom.sun.management.jmxremote.ssl=false",
"-Dcom.sun.management.jmxremote.authenticate=false",
** Replace <server-hostname> off course with ...
You can use JProfiler:
Installation procedure for Jprofile is documented in http://resources.ej-technologies.com/jprofiler/help/doc/help.pdf, see section B.3.10 Attaching To JVM.
By using jpenable, you don't have to change anything in your Mendix configuration.
Some screenshots here: Profiling Mendix using JProfile