Hi John,
This is not a supported feature in the Guest console and sponsored guest User db. You can only maniplate the password generation rules.
If you need to import specific named guest accounts with specific passwords you can import them into the ISE Admin console\Administration\Identities\Users and associate them with the "Guest" user group. If you also need time and date restricitions, they will have to be manually created using custom Common Time and Date Conditions (in Policy Elements) and referenced in your Authorization Policy.
