From Justin:

Once they [the Windows/MacOS binaries] are building successfully downstream (your ART build), then a ticket can be opened with ART: https://issues.redhat.com/projects/ART saying ~"Please extract X from image Y by running Z and publish them to the openshift mirror in directory ....". Once they are being synced to the mirror, ART can also help you get them signed and published to the customer portal (technically Software Production has to do this, but ART can help get the ticket open).