Old topic but i'll answer anyway for future references, I looked to find if it was possible to change the display of combopoints on a custom class I had created (the class was using mana, rage and energy at the same time) and after dozens of changes and try in the core itself and in the interface (even with some test on interface addons) it wasn't working, I've come to the conclusion that it was hardcoded to show only for rogues&druids.
BUT. Warrior use combopoints, so there are here even if we can't see them (If you wonder, the spell Overpower generate a combopoint if the target dodge, then you can use the spell, some bodging from blizzard) with some try I've figured out that Eluna can track these combo points and i've done a little lua code and added some graphics with it to show the combos points in "real" time.
TLDR : From my personnal test you can't except if you do it with Eluna installed in your core.
