With V5 and V6, you must do a full install AC into another computer, then create a fake database (just to get it going, when it asks for provider and office info I just fill boxes with random letters), then do a restore from a saved backup.
Be cautious, when you use this technique, you must first install the same version of AC that created the backup (.enc) file. That is, you can't use a version 5.029-created backup to restore a new version 6 installation.