During Beta there was a button next to the Make X amount. You would press that button, and then type in the number you wanted to make. It would then change to show that you were making X amount on the menu.
I haven't had a chance to log in yet (still at work) so I'm not sure if there was another step there or not.
And just to be clear.. when you press the button to set how many to make, you'll just be typing the number directly into chat, as if you were talking to another player.. there is no box or anything that you'll type it into.
Really would have helped if I'd refreshed that page before replying.. hehe.