Lamont Library has informed DOCOMOMO US that the Woodberry Poetry Room can be visited by researchers upon request:
I was reading about the Woodberry Poetry Room controversy, and I noticed you said the room was not open to the public. While Lamont Library is not open to the public, outside researchers may use the Poetry Room, though they should contact the curator, Don Share, firstname.lastname@example.org, first.
Lamont Library Reference
DOCOMOMO US notes that more information can be found here  and that visitors should be aware that photography within Lamont is not allowed without the permission from the Office of the Librarian of Harvard College. See their website  for policies.