During World War 2, the United States government published the Simple Sabotage Field Manual, which is a short pamphlet about how an untrained citizen can safely be a nearly invisible but still meaningful obstacle against the fascist regime they unfortunately live in
Station engineers will find it quite easy to overmodulate transmissions of talks by persons giving enemy propaganda or instructions, so that they will sound as if they were talking through a heavy cotton blanket with a mouthful of marbles.
Some of it can be adapted as needed, and some of it is stuff that quislings - as they are mentioned here, or as we would know them, 'the blue team' - already does as part of its own playbook, but that doesn't mean it can't also be used against them too