A quill with the slit cut off-centre (to the left seen from above, if you are right handed) will work nicely. You might try grinding down the left side of a steel nib in an attempt to simulate this - I wouldn't expect it to be a resounding success, though. It may be that an Automatic Pen would work since it is, after all, a mutated ruling pen.
I've had middling success with this sort of thing with reeds, but there's no question of persuading one to flow for hairlines indefinitely, with or without an reservoir - whereas a quill will definitely do this for you. If you want to stick with steel nibs Erica is probably right about doing the hairlines with a pointed pen - that was certainly the prescribed method in late 19th century textbooks. Jackson, by the way, is not known for using steel pens.