At the moment the only supported way of obtaining the deployment YAML template is through subscription-manager.
In case the system is not directly registered or is completely disconnected, this is not possible and there is no alternative way to get it.
Other MW products provide this way of getting the yml template (see https://raw.githubusercontent.com/jboss-openshift/application-templates/ose-v1.4.11/sso/sso72-x509-mysql-persistent.json)

CORRECTION:
the template is also available publicly and it is maintained here: https://github.com/3scale/3scale-amp-openshift-templates
we are missing documentation on this in the deployment phase.