You can't use parameters for table and column names, only where expressions are allowed. So you have to use string substitution for this:
$tableQuery_comment = <<<query
CREATE TABLE IF NOT EXISTS `{$tablePrefix}comment` (
`cmt_id` bigint(20) unsigned NOT NULL AUTO_INCREMENT,
`cmt_obj_id` bigint(20) NOT NULL DEFAULT '0',
`cmt_author_name` tinytext NOT NULL,
`cmt_author_email` varchar(100) NOT NULL DEFAULT '',
`cmt_author_url` varchar(200) NOT NULL DEFAULT '',
`cmt_author_ip` varchar(100) NOT NULL DEFAULT '',
`cmt_date` datetime NOT NULL DEFAULT '0000-00-00 00:00:00',
`cmt_content` text NOT NULL,
`cmt_approve` varchar(20) NOT NULL DEFAULT 'yes',
`cmt_agent` varchar(255) NOT NULL DEFAULT '',
`cmt_parent` bigint(20) NOT NULL DEFAULT '0',
`user_id` bigint(20) NOT NULL DEFAULT '0',
PRIMARY KEY (`cmt_id`),
KEY `cmt_obj_id` (`cmt_obj_id`),
KEY `cmt_parent` (`cmt_parent`),
KEY `user_id` (`user_id`)
)
query;