The latter is called cracking , and is often performed by morally bankrupt juvenile delinquents whose accounts aren't worth the disk space they consume. First, i had to figure out the spec for the IR codes. A Sharp decoder that you can pick up at radio shack and an oscilloscope on the output of the decoder is all you need. For the Panasonic TV and VCR that i have, the codes are 22 bits, encoded as pulse lengths modulating a 40 kHz carrier.
Longer pulses are ones, shorter pulses are zeros.
The actual hardware is just a ring oscillator at 40 kHz that can be enabled or disabled, with a PIC converting the serial input from the computer into pulses to enable or disable the oscillator. It also decided to convert every microphone blip into 2s, so every time i coughed or dropped the microphone, it switched the TV to channel 2. Of course, it would be a lot easier to just put new batteries into the TV remote. This will probably just get bought instead, because it really stinks when you can't even trust your own test equipment. Before our house switched over to compact fluorescents, turning on an incandescent meant that you got visually kicked in the eyes.