a Page of Nerd Songs contains this "poem", which might be the first published use of the word "hacking" in the modern understanding of it:

The following parody of Carl Sandburg's "Chicago" appeared in the newsletter of the Tech Model Railroad Club at MIT back in the fifties. The TMRC evolved into one of the very first computer clubs, and this may be the first published use of the term "hacking" as presently used...

Switch Thrower for the World, Fuze Tester, Maker of Routes,
Player with the Railroads and the System's Advance Chopper.

Grungy, hairy, sprawling,
Machine of the Point Function Line-o-lite:
They tell me you are wicked, and I believe them; for I have seen your
painted light bulbs under the Lucite, luring the system coolies
Under the tower, dust all over the place, hacking with bifurcated springs
Hacking even as an ignorant freshman hacks who has never lost occupancy and
has dropped out.
Hacking the M-Boards, for under its locks are the switches and under its
control the advance around the layout.

Hacking!