So I have a question for the developers at Splunk. Why is there no option inside of general settings that allows us to specify an SSL cert to be used for the server????? Cisco has this feature in their FirePOWER software. Hell, it will even generate the certififcate for you. This is feature that is severaly needed in Splunk and I'm not the only person who seems to think so. I have to talked to several people from several other establishments like where I work and they all have the same qissues and questions.
Are you asking for a way to do this through the Splunk Web UI? If your question is more general, you can use your own certificate by adding it to the settings in web.conf. See Secure Splunk Web with your own certificate in the Securing Splunk Enterprise manual, if you haven't already discovered this content.