Ok, so let me try to clarify. There are two types of three-button headphones: (1) the ones that only work with an iPhone, meaning on these you will likely only have center button functionality if you use them on Android; and (2) the ones that work with Android, meaning on these you will have three button functionality.
Now, if you get an Android compatible set (such as the Nocs NS200, which I have), on most Android phones, you can use all three buttons. And through various applications (like Headset Button Controller, etc), you can in fact configure the three buttons to do various different things.
Now, things are different with the HTC One, as far as I can tell. Even if you have an Android compatible headset, the HTC One prevents you from reconfiguring how the buttons work. In this case, the back/forward buttons appear to be hard wired to skip track/previous track. On the Nexus, for example, I used Headset Button Controller to make the back/forward buttons control volume up/down, and then long press to skip/previous track. Can't do that on the HTC One - you're stuck with skip/previous. And long presses don't work, period.
I don't know why this is, but it seems to be something that Sense does. I'll try a custom rom to see if that helps, but it's kind of bull**** that I have to do this - thanks, HTC.