JRE installation is the only requirement other than Splunk (and make sure to set JRE path properly):
* https://docs.splunk.com/Documentation/AddOns/released/JMX/Installationsteps
* https://www.baboonbones.com/php/markdown.php?document=jmx/README.md
Of course you need to have JMX enabled on the monitored application's side.