While the options available could vary slightly depending on the version of your Jive instance, for the current, out of the box options you might find the following section on the documentation helpful:
Jive 7 - Single Sign-On
Jive 8 - Single Sign-On
Cloud external - Single Sign-On
Cloud internal - Single Sign-On
Additionally, if you are looking for a custom solution I would suggest submitting a case in your Jive Community secret group where we can get you engaged with our Professional services team who can work with you to develop a custom integration which works with your custom application.
Thanks for replying Jesse.
Sadly, the only option that they all offer is doing the SSO with SAML, which I was hoping wasn't the only one. And while how you manage your users for SSO behind SAML is configurable, it's still SAML which I've found to be fairly inflexible.
Sorry to hear the current options don't meet your specific needs.
As a next step, if you are interested in a custom solution for your instance I would suggest opening up a case in your Jive Community's secret group where we can setup an engagement for your with our Professional Services team.
Additionally, if you would like to see alternative methods available in future releases I would encourage you to create an idea in the Ideas for Jive space where our product management reviews top rated ideas for possible inclusion into future releases.