Removing white space before a character in text field.

As the title says: How can I remove the white space before a character in a text field so that it aligns flushed with the text frame.
And no, it is not just a font creator thing that can't be changed. There's a hack not involving scripts or outlining text. I've done it before, I just forgot.
I tried using Story for optical alignment, but it is not doing it for me. I think it may have something to do with negative margins.
If you remember the hack, please share.
