It's completely possible. Armour stands have different tags which can be set so you can just set the helmet of the armour stand, make it invisible and then just attach it to that specific entity. If the entity dies, just remove the armour stand. However, it would be a waste of time. I'd much prefer a site update or Dragon Tombs to arrive. Aikar wouldn't use command blocks.
http://minecraft.gamepedia.com/End_Rod No armor stands needed. Just type in the command /replaceitem entity @e slot.armor.head minecraft:end_rod I was excited when I first read that thinking it would work on any mob! It unfortunately doesn't work with every mob. Just mobs that can actually wear helmets (Zombies, Zombie Pigmen, Skeletons, Wither Skeletons), plus Villagers (but not Witches). And of course us players so at least it's something to try in single player mode. Lol now to find a new horse skin! I will edit in a pic of me doing thus later Edit:
Enraged endermen? Have a baby armor stand riding an enderman with an end rod on its head. Unicendermen.
