Bryan,
Once you have created the attribute in the Attribute Manager, you need to add it to the CAD Document type in the Type Manager
Specify the same name as the Creo Parameter (in all upper case letters) as the Internal Name in order to do implicit mapping. On the Choose Global Attribute screen, select the attribute you created in the Attribute Manager and then set the attribute properties (display name, etc.) on the third step.
This will get the attribute to appear in the table view manager, and the attribute will map to the Creo parameter the next time the CAD file is checked in.