Well, I usually 4 box a similar setup. I use wineq, pretty essential to doing it on 1 box, with the G15 keyboard. My first character, and my main is a shammy, but I usually box a warrior, the shaman, a monk, then either a necromancer or a paladin, depending on which one I am leveling up. I can't run 5 without lag on my one system, so am looking at alternatives still.

I use the macro keys on the G15 extensively, with usually a 'line' being for 1 character. I used to only 3 box, so at that time, I had each line of the G keys for each character. I may switch it up a bit now that I box more, not sure yet. I record the macro for each key by first selecting the screen in the msacro using the wineq key shortcuts, then doign the actions, usually using the same hotkeys in game for each character, ie, each key will select screen, then hit hotkey 0 (for an assist usually to assist the main tank character) then hotkey 5 (on shaman casts slow, on necro sends pet in to attack then starts casting after some delays, etc)

Anyway that is my basic setup. I have tried a couple of keyboards, but always got confused multi-boxing that way. I am looking at a KVM switch for multi boxing, or Synergy, just DL'd it, so may see how it does. If you have any further questions, feel free to ask.