I managed to supply my own SSL certificate and start Cockpit but the ovirt-cockpit-sso service is all messed up so you need to configure a Linux user with password to login. The SSO service logs following errors.
Jan 09 23:21:09 localhost.localdomain systemd[1]: Starting oVirt-Cockpit SSO service...
Jan 09 23:21:09 localhost.localdomain prestart.sh[2669]: /bin/ln: failed to create symbolic link ‘/usr/share/ovirt-cockpit-sso/config/cockpit/ws-certs.d/ws-certs.d’: File exists
Jan 09 23:21:09 localhost.localdomain systemd[1]: Started oVirt-Cockpit SSO service.
Jan 09 23:21:09 localhost.localdomain start.sh[2676]: (standard_in) 1: syntax error
Jan 09 23:21:09 localhost.localdomain start.sh[2676]: Installed cockpit version:
Jan 09 23:21:09 localhost.localdomain start.sh[2676]: /usr/share/ovirt-cockpit-sso/start.sh: line 9: [: : integer expression expected
Jan 09 23:21:09 localhost.localdomain start.sh[2676]: Installed Cockpit version is old, at least 140 is required for ovirt-cockpit SSO
I'd file a bug in bugzilla but as I stated before it's not working either.