It’s probably not what you want, but I’ve been using parallel ruler and vanishing point assistants to draw hatching over a large area. That way I can control the line weight with pen pressure, but all my lines will be straight.
As for the brush, the worn-out g-pen brush from Ramon’s InkP package is very good for hatching.
Here’s an example with this method (the background and the shadow):
I think I used it in a few other pictures too, but I’m not sure right now.