Thread:RRabbit42/@comment-5055855-20121214230802/@comment-961279-20121222164442

At the bottom of the screen in the toolbar, you should have an "Admin" link. That will take you to the Admin Dashboard, and from there, you can go to Wiki Features. (Or you can go right to it via Special:WikiFeatures.)

You will find Chat in the Labs section and can enable it from there.