The specifics followed a suggestion made by Spock, when asked how to repel the Klingons, who offered that they "throw tribbles at them." Emergency Defense Plan B consisted of just that: throwing tribbles at Klingons.
The execution of Emergency Defense Plan B involved personnel of the crew of USS Enterprise luring tribbles into the transporters and beaming them into nearly every compartment aboard the Gr'oth that could hold them, including the engine room and transporter room.
Later, the glommer was also returned to the Klingons, but it proved ineffective with such large numbers of tribbles.
Dr. Leonard McCoy speculated that the Klingons would have to learn how to treat their giant tribbles with neoethylene as he had theirs, and soon, or the Gr'oth would not be large enough for all of them. (TAS: "More Tribbles, More Troubles")