I understand what you mean, but what would be the effective difference here between stop and pause? The only thing I can think of is, possibly, a difference in the display. If a stop mode were implemented, you'd have to either press the stop button before you turned it off the previous time it was on, or press it as soon as it turned on. You can do the same thing with pause.

Or maybe you mean that you want it to be not playing music every time you turn it on. You might be able to do this with Hijack's IR Translations, telling it to pause the player every time it came on. I have some doubts, though, since I seem to remember that pause is a toggle and there's no way to get the current state. Can someone help me out on that piece of knowledge?