With only a power toggle button on the Philips, I would imagine that all the database entries would utilise power toggle codes rather than discrete on/off codes, which by definition would require two buttons.

Following the instructions for Learning key functions just learn the on code to, say, the POWER button and the off code to the FAV button; chosen only because of it's being directly below the power button and easy to remember. Obviously if you need that button for something else, just use any "redundant" button, assuming of course there is one.