Update User Status / Trigger User Tranistion via REST API

Summary:

I have successfully followed the below documentation to setup a custom user status & user transition.

https://docs.oracle.com/en/cloud/saas/sales/oacts/how-you-set-up-user-statuses-and-user-transitions.html#How-to-Raise-a-Business-Event

It works great in the UI and does exactly what I need it to do. However, I would like to be able to trigger the action in a similar fashion to the other actions that are available to submit via the Contract REST API:

I'm not seeing that this is available in the standard REST API however. Has anyone successfully triggered a custom user transition via REST or SOAP?

Thanks!

Lee