Hello,

I've dual boxed a number of different combinations of classes and am quite familiar with it. As for keybindings, usually I set:
2-4: standard dps caster rotations
5-7: healing macros
8-0: AOE and oh-sh1t buttons (Ice Block, Fade, etc)
And for melee tank rotations, I usually put it in the action bar above the normal action bar, and just click them. I was able to two-shot most mobs this way, and when fighting elites:
I use mouse clicks for tank abilities with my right hand, and with my left hand:
I type 2 3 4 3 4 etc when I need to dps
I type 5 7 6 7 5 when I need to heal

Recently, I started tri-boxing with my main account that has a level 70 already. That being said, my first composition is DK-Mage-Healadin, all at level 70.
How do you set up your key bindings? I originally left it the same as above just because I'm already "used" to the setup, but I feel that I need to press dps rotations AND healing rotations at the same time with my left hand, and it's quite confusing. Is there a better way to do this? Btw I only do this when I'm trio-ing 5-man elites like Durnokk the Hungerer. When I'm fighting 3 man elites, I'm not as anal in dps and heals because it's not as crucial.