5 years late, but it is possible:-

• Extract unique user names from bbs files and insert into mlf2_userdata
  
• Extract info from all your bbs files and insert into temp_post table
  
• ALTER TABLE mlf2_userdata ADD INDEX MYTMP (user_name)
  
• UPDATE temp_post t SET t.user_id = (SELECT m.user_id FROM mlf2_userdata m WHERE m.user_name = t.user_name)
  
• ALTER TABLE mlfs_userdata DROP INDEX MYTMP;
  
• Update temp_post.pid with PREV> from bbs file
  
• Update temp_post.tid with incremental int WHERE temp_post.pid is not set
  
• Repeatly update temp_post.tid a (SELECT b.tid WHERE b.id = a.pid)
  
• Update temp_post.text with LINKURL bbcodes
  
• Update temp_post with LINKIMAGE bbcodes
  
• INSERT INTO mlf2_entries SELECT .. FROM temp_posts
  
• DROP TABLE temp_posts;
  
• Clean up user accounts

CREATE TABLE `temp_posts` (
`id` int(11) NOT NULL,
`pid` int(11) DEFAULT '0',
`tid` int(11) DEFAULT '0',
`myid` int(11) DEFAULT NULL,
`myprev` varchar(20) DEFAULT NULL,
`mynext` varchar(1024) DEFAULT NULL,
`time` timestamp NOT NULL DEFAULT CURRENT_TIMESTAMP,
`user_id` int(11) DEFAULT '0',
`name` varchar(255) NOT NULL,
`subject` varchar(255) NOT NULL,
`email` varchar(255) DEFAULT NULL,
`ip` varchar(128) DEFAULT NULL,
`text` text,
`mylinkname` varchar(256) DEFAULT NULL,
`mylinkurl` varchar(512) DEFAULT NULL,
`myimage` varchar(512) DEFAULT NULL
) ENGINE=InnoDB AUTO_INCREMENT=10 DEFAULT CHARSET=utf8;