Directions: 2nd Floor in the new building. This bathroom is tucked away as you leave the cafeteria towards the Auditorium Building/bridge. The walls are all red, and on your right will be a row of stools and a counter, the traditional "man/woman" bathrooms on your right, and the single room, accessible restroom is on the left side right after the stools. It's pretty much the last thing before you start heading towards the old building.
Comments: You do need an ID to enter. If you're a clever one or don't care, the last time I checked their daytime security guard at the front entrance of the building is really, really lazy. Basically if you are used to jumping through these hoops here's some pointers, but if you're not it might not be the best idea. Sometimes you can gain access with ANOTHER college ID (expired ancient whatever) from IL and ask to use the library. Technically that's how college libraries work.