https://web.archive.org/web/20051023131548/http://listserv.l...
And here's the (unrelated) "paper with a most hilarious and offensive name":
https://web.archive.org/web/20080903094328/http://findarticl...
There are also the Tech Model Railroad Club dictionaries of 1959 and 1960, which include "hacker":
http://www.gricer.com/tmrc/tmrc-dictionary-intro.html
Why does this not count as an earlier recorded usage? Is it because those dates have not been independently verified?