Sadly, not a straight 1 to 4 setup, its a bit complex so its easier to multibox. Basically I've created keys for every skill for each character. They can share the same hotkey in some cases depending on the functionality. For example:

1 = Static Charge on SC monk and mouse1 for the other 3 chars
2 = Breath of Heaven on SC monk + Blinding Flash on heal monk + Condemn on Crusader + Sprint (3s)
3 = Inner Sanctuary on heal monk + Shield Glare on Crusader
4 = Judgement on Crusader (it messes up Cyclone Strike so u wanna have all mobs pulled before using this)
5 = Laws of Hope on Crusader (10s) + Mantra of Healing (0.7s) on heal monk + Ignore Pain on Barb (11s)
6 = WarCry (10s)
7 = Threatening Shout (3s)

I try to use more keys because when u use the same hotkey for 2 or more skills on the same char, sometimes u dont cast the skill. Not a problem when its a low cooldown skill that u can spam, but when it's a timed buff/debuff that u rely on, u can easily die. For example Ignore Pain which I have every 11 secs. If I share it with WarCry or Sprint hotkey and eventually I send it both at the same time, I may miss Ignore Pain, since I have it on trigger once and run the risk of having 11 secs of Ignore Pain downtime which will most likely get me killed. I don't see this when each skill has its own hotkey. Of course I'm not mashing all 7 buttons. My mouse takes care of 2567 and I just focus on 134, right/left clicks.

Since SC monk needs certain rotation when u use 2 generators, it makes it a little bit difficult to make keys work and not lose your F&R buff. My rotation is:

1. Cyclone Strike to pull everything really close and proc F&R on SC charge monk.
2. Inner Sanctuary + Shield Glare + Judgement
3. Main attack to get Assimilation stacks (only 3 hits needed).
4. Static Charge on different mobs to spread the debuff
5. Main attack to proc it even more

On the meantime, I spam the other skills that are on 2567. I know, it doesn't sound simple, but u get used to it pretty fast.