There's a hardware element involved, here. Early cable boxes could be hacked by screwing with the circuits. They would then authorize previously unauthorized content.

Some of the newer boxes require a special card be inserted to act as a key.

Regardless, you'll need someone who knows the schematics of your particular model. As time has gone on, defenses have become more sophisticated. Also, you may not have long to enjoy the box. Cable companies like to send a "kill signal" to boxes that aren't playing nice with their system. It essentially bricks the cable box. It's mostly for anyone trying to use a non-authorized box, but it might affect hacked boxes as well.