Hi Matt,
Never mind, I also logged with support, and they informed me that this feature is only available in Linux Ultimate. Pity that nowhere in the release notes does it mention anything like this.

Even using the cbbCommandLine help for editBackupPlan, it shows an example command to add a PreAction script, but when trying to use it just responds with a cryptic error message rather than a more helpful, "Sorry, pay us more and we'll enable this feature for you" ..