Well, you can "hide" buttons or "show" them during combat the way you want (according to combat points, to enemies casts, to cooldowns etc), but it won't be really hidden. What I mean is, if you click where your kidney shot usually is while it's "hidden" like that, you WILL kidney shot. But you won't see the button on your screen.
However, if you're not a clicker (which, on a side note, I strongly advise in PvP, especially as a rogue as you need quite a lot of mobility, and you can't afford to keyturn or to have downtimes in your abilities while turning with your mouse
), you can make unclickable buttons that pop wherever you want, whenever you want, just to let you know that you should use ability X now, or ability Y.