I've tanked some pretty crucial content in this game and have never used a single macro and play on a controller. My personal opinion is that it's inefficient beyond notifications ie provoke, hallowed ground, or mechanics. It also limits your ability To certain degrees.

As far as starting tanking with dark knight I would recommend leveling a pally first honestly and at least getting the hang of it before moving onto dark knight. Dark knight while not like pally is a bit intricate and deliberate in its play style and I think trying to learn tanking in the game and dark knight as a class at the same time may be a bit crucial, but that doesn't mean it cant be done. Either way you will want some gladiator and marauder cross class skills if you plan on doing anything besides dungeons.