[ShiningArcanine]

I did a little experimenting with queries and came up with the following.

Running this should turn fulltext on:

ALTER TABLE post ADD FULLTEXT INDEX (title,pagetext);
ALTER TABLE thread ADD FULLTEXT INDEX (title);
UPDATE `setting` SET `value` = '1' WHERE `varname` = 'fulltextsearch' LIMIT 1 ;

Running this should turn fulltext off:

UPDATE `setting` SET `value` = '0' WHERE `varname` = 'fulltextsearch' LIMIT 1 ;
ALTER TABLE `post` DROP INDEX `title` ;
ALTER TABLE `thread` DROP INDEX `title`;

Edit: By the way, I recommend running these queries one at a time or in PHPMyAdmin.

Another Edit: I just fixed a careless mistake that didn't index pagetext. ^_^;;

3rd Edit: By the way, if you run those queries, you will want to go to vBulletin Options in the control panel and click "save." Otherwise the cached copy of $vboptions will contain the old settings.