I'm doing this against our MySQL and MS SQL servers via custom php extensions. It works well & is easily incorporated within the MediaWiki interface so none of my users is the wiser.
Oh.. thanks, I see... But could you please share some sample of the extensions you wrote or give some clue? My knowledge is very limited.
thanks,
Pablo
Regarding your specific request - the comment at the top of the specialasksql.php code suggests that it would only work for queries against the cur table.
Al.