Frederick Franz studied Biblical Greek at the University of Cincinnati with the intention of becoming a Presbyterian preacher (Penton, M. James (1997). Apocalypse Delayed: The Story of Jehovah's Witnesses (2nd ed.). University of Toronto Press. p. 174. ISBN 0-8020-7973-3.) He was also quite the linguist, speaking about half of the major Western European languages.
Albert Schroeder was a bit of a linguistic genius as well, earning his degree at the University of Michigan (according to his Dutch Wikipedia page, he did this in just one year, although there's no source to back it up - http://nl.wikipedia.org/wiki/Albert_D._Schroeder).
George Gangas lived in Athens, where he learned Greek. Not sure which school he studied at (if at all).
As for Hilton Menschel and Nathan Knorr, I'm not certain. My Dutch colleague who tends to know these kinds of things said he was confident that Knorr had not contributed to the New World Translation, but he couldn't tell me where he knew that from.