Hi Ellen -
The sweater's stitch pattern and shape was created (in collaboration with Dominique's design vision), hand-dyed, and knit by the show's laundry and crafts person, Amy Micallef. She has a website here:
http://www.amymicallef.com/ where you can see some of her knit projects, her Organ Bank, her etsy stuffs, and theoretically get in touch (though I'm not sure how old the email attached to the contact me page is). At the very least, you can drop her a note via the stage door (address it to Amy Micallef c/o the Wardrobe Dept) if you want her to get in touch. Cheers! :)