I thought this macro would be easy...

[Multibocks]

nm =X

[Maxion]

If you don't spam it too fast, something like the macro I use for cleansing should work pretty well, and adding more commas would let you spam it faster:

/castsequence [target=player]reset=5 ,,,,Remove Curse
/castsequence [target=party1]reset=5 ,,,Remove Curse
/castsequence [target=party2]reset=5 ,,Remove Curse
/castsequence [target=party3]reset=5 ,Remove Curse
/castsequence [target=party4] Remove Curse

With the various party# replaced with toon names, and you can add commas on the other side of the spell name to be extra sure it won't recast it on any of them if you have room and added the extra commas before it.

This macro is based on the principle that the earliest sequence currently at a valid spell will fire first at each press of the button.

Making it /click based with one or two castsequences in each, would give you more room to make it however you want, if you are not using macaroon or a similar addon to get extended macro lengths in the first place.

[Owltoid]

Have you actually tried that Maxion because I'm not sure it will work. I'm nearly positive I tried a similar solution and it failed.

[Ualaa]

Maxion says, he does use the macro for cleansing.

I'm assuming Remove Curse and Rejuvenation would work the same.
It is interesting in that its the reverse of how most stagger things.
With the no actions early, and the initial action as the last line.

Interesting solution.

[Owltoid]

I'm not surprised a cleansing macro would work, but I think that's because cleansing won't cast if there is nothing to cleanse. Rejuv is going off regardless of if there is already one on the target.

[Dwarven]

What about something like this:

/castsequence [target=A] reset=5/combat rejuvenation,nil
/castsequence [target=B] reset=5/combat rejuvenation,rejuvenation,nil
/castsequence [target=C] reset=5/combat rejuvenation,rejuvenation,rejuvenation,nil
/castsequence [target=D] reset=5/combat rejuvenation,rejuvenation,rejuvenation,rejuvenatio n,nil
/castsequence [target=E] reset=5/combat rejuvenation,rejuvenation,rejuvenation,rejuvenatio n,rejuvenation,nil

Spammable, and shouldn't waste mana on extra rejuvs even if you spam it after all rejuvs are up. You can replace the last line with

/use [target=E] rejuvenation

if you're paying enough attention to stop spamming once they're all HoTted up.

[Owltoid]

Dwarven, how many times are you spamming the button before your multicasting software (HKN for me) tells a new signal? I'm pushing "d" the entire time, a few times a second. With your solution, if you mistime your spamming you will cast two rejuvs on the same target before switching. The reason the macro I posted before, with many nils at the end and reset on target, works is because you can spam it as much as you want and it will only cast that new rejuv when the target changes.

I'd like others to test their solutions and see if they'll really work. I spent at least 4-5 hours on this problem and I think I've tried every solution posted in this thread, already, but I could be wrong.

[Dwarven]

Dwarven, how many times are you spamming the button before your multicasting software (HKN for me) tells a new signal? I'm pushing "d" the entire time, a few times a second. With your solution, if you mistime your spamming you will cast two rejuvs on the same target before switching.

No multicasting software required, it's a macro that'll work directly in game with no outside help.

Just tested it (with renew, but I don't think switching it to rejuv should break it)... it worked whether I pressed it 5x a second, or 1x a second. It should work no matter how fast you push the button (unless, of course, you press it less than once every 5 seconds :P)

[Owltoid]

very nice, then! I haven't tested it but it's a much smoother solution than the one I had.

[Ghallo]

Maxion's solution will work because the spells aren't "in position" yet.

With:
/castsequence [target=player]reset=5 ,,,,Rejuve
/castsequence [target=party1]reset=5 ,,,Rejuve
/castsequence [target=party2]reset=5 ,,Rejuve
/castsequence [target=party3]reset=5 ,Rejuve
/castsequence [target=party4] Rejuve

The first 4 don't advance because the spells don't match the spell that cast successfully.

Personally, I'd have this go "backwards" and modify it like this:
/castsequence [target=party4]reset=5 ,,,,Rejuve,nil
/castsequence [target=party3]reset=5 ,,,Rejuve,nil
/castsequence [target=party3]reset=5 ,,Rejuve,nil
/castsequence [target=player]reset=5 ,Rejuve,nil
/castsequence [target=party1] Rejuve

So that if you spam it, they will always cast on the "leader" if you are spamming it "too much"

No HKN, IS, or Keyclone needed. Just put this on the same key on all toons.
Edit: As stated by Maxion - you need to add leading commas per your spam rate.