HK use two key power scheme, one key for off and another for on. With only one power key on the cable remote, you need two devices to get both commands. You could program the device with code 1304, key move the power command to another key like so:

1. audio device
2. press and hold SETUP for two blinks
3. enter 9 9 4
4. press the power key
5. pick another key other power, press

Now reprogram the audio device with code 0110, the power command from code 1304 will still be there, now you have a device with both commands present.