I realize this is an old post, but in case you can still use it to add to the importer, the database structure for the knowledgebase in v. 6.x of WHMCS is:
--
-- Table structure for table `tblknowledgebase`
--
CREATE TABLE IF NOT EXISTS `tblknowledgebase` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`title` text NOT NULL,
`article` text NOT NULL,
`views` int(10) NOT NULL DEFAULT '0',
`useful` int(10) NOT NULL DEFAULT '0',
`votes` int(10) NOT NULL DEFAULT '0',
`private` text NOT NULL,
`order` int(3) NOT NULL,
`parentid` int(10) NOT NULL,
`language` text NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ;
-- --------------------------------------------------------
--
-- Table structure for table `tblknowledgebasecats`
--
CREATE TABLE IF NOT EXISTS `tblknowledgebasecats` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`parentid` int(10) NOT NULL DEFAULT '0',
`name` text NOT NULL,
`description` text NOT NULL,
`hidden` text NOT NULL,
`catid` int(10) NOT NULL,
`language` text NOT NULL,
PRIMARY KEY (`id`),
KEY `parentid` (`parentid`),
KEY `name` (`name`(64))
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ;
-- --------------------------------------------------------
--
-- Table structure for table `tblknowledgebaselinks`
--
CREATE TABLE IF NOT EXISTS `tblknowledgebaselinks` (
`categoryid` int(10) NOT NULL,
`articleid` int(10) NOT NULL
) ENGINE=InnoDB DEFAULT CHARSET=utf8;
-- --------------------------------------------------------
--
-- Table structure for table `tblknowledgebasetags`
--
CREATE TABLE IF NOT EXISTS `tblknowledgebasetags` (
`id` int(10) NOT NULL AUTO_INCREMENT,
`articleid` int(10) NOT NULL,
`tag` varchar(64) NOT NULL,
PRIMARY KEY (`id`)
) ENGINE=InnoDB DEFAULT CHARSET=utf8 ;