I have reinstalled my interlanguage management at test.wikipedia.org. For those interested, I have also committed the code to the CVS. It is turned off by default; to turn it on, set $wgUseNewInterlanguage = true ; in your LocalSettings.php
For your local installation, you'll need to create a "wiki-intl" database, with tables "ilinks" and "recentchanges":
CREATE TABLE ilinks ( lang_from varchar(5) default NULL, lang_to varchar(5) default NULL, title_from tinyblob, title_to tinyblob, target_exists tinyint(1) default NULL ) TYPE=MyISAM;
CREATE TABLE recentchanges ( user_name tinyblob, user_lang varchar(5) default NULL, date timestamp(14) NOT NULL, message tinyblob ) TYPE=MyISAM;
Happy hacking!
Magnus