I think I answered this offline via your SE, but for the benefit of everyone else...
The actual certificates in the Global Certificate list do not get stored on MWG 6.x directly. Only the SHA1 thumbprints get stored.
So in order to do something similar, you could create rules that use the hash instead.
SSL.Server.Certificate.SHA1Digest is in list Certificate Hash Whitelist
and paste the hashes into the appropriate string list.
You should have the functional equivalent of MWG6 using the SHA1 hashes instead of the entire certificate.