I'll craft one in eotn just to see if it's dyable.
Edit: no I won't. According to
the talk page, the eotn merchant version isn't dyable either.
Edit2: check
this older Q&A thread for more confusion. At least one post suggests that fire wands dropped as loot in prophecies are dyable. At least from the starting post it could have saved you some money not buying one in the command post

.
That's all the info I can find on dying fire wands on this forum dating back to august 2006. I think you're going to face the tough job of finding a 20/20 fire wand dropped as prophecies loot if you really want a dyable perfect fire wand.