okay, i was able to get the certs installed

with the command line steps documented
here.
# zmcertmgr deploycrt comm /tmp/certs/commercial.crt /tmp/certs/verisign_chain.crt
** Verifying /tmp/certs/commercial.crt against /opt/zimbra/ssl/zimbra/commercial/commercial.key
Certificate (/tmp/certs/commercial.crt) and private key (/opt/zimbra/ssl/zimbra/commercial/commercial.key) match.
Valid Certificate: /tmp/certs/commercial.crt: OK
** Copying /tmp/certs/commercial.crt to /opt/zimbra/ssl/zimbra/commercial/commercial.crt
** Appending ca chain /tmp/certs/verisign_chain.crt to /opt/zimbra/ssl/zimbra/commercial/commercial.crt
** Saving server config key zimbraSSLCertificate...done.
** Saving server config key zimbraSSLPrivateKey...done.
** Installing mta certificate and key...done.
** Installing slapd certificate and key...done.
** Installing proxy certificate and key...done.
** Creating pkcs12 file /opt/zimbra/ssl/zimbra/jetty.pkcs12...done.
** Creating keystore file /opt/zimbra/mailboxd/etc/keystore...done.
** Installing CA to /opt/zimbra/conf/ca...done.
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NOTE however, the GUI installation still fails with the error noted earlier...with the same *.crt files!