How to customize KubeSchedulerConfiguration of the default openshift scheduler

Hi. I'm interested in adding a scheduler extender to OCP 4.10/4.12. I understand that I need to configure the extender in the KubeSchedulerConfiguration used by the default openshift scheduler.

I can see this resource in the configmap openshift-kube-scheduler/config. But the configmap can't simply be changed, as the changes are overwritten immediately.

How can I make this change persistent?

Thanks,
Mike