I am surprised the Harmony dataset for your particular Panasonic model (TH-42PY800) does not contain any Inputxxx command. Maybe you should try a similar model like the Panasonic TH-42PY700. The dataset for this model contains the following list of input commands: InputAntA, InputAntB, InputComponent1, InputComponent2, InputNext, InputPC, InputTuner, InputVideo1 to InputVideo4. The "InputNext" command is obviously a cycling command but most of the other input commands (like InputVideo1 to InputVideo4) are discrete commands. You need to test them (via device mode).