Good morning,
There are several ways that you can accomplish this:
1) If it is a brand new environment with no policies and such, then you can use the ssgbackup and ssgrestore scripts
2) The Gateway Migration Utility as it will migrate over all dependencies related to service and policies. It also has the ability to migrate all the setup including Private keys and Trusted Certificates
3) Using the restman API to export and import in the
trusted certificates (https://gw.example.com:8443/restman/1.0/doc/restDoc.html#1.0/trustedCertificates)
private keys (https://gw.example.com:8443/restman/1.0/doc/restDoc.html#1.0/privateKeys)
Sincerely,
Stephen Hughes
Broadcom Support