This is just a cut and paste from what I've posted on the Aion Source forum discribing my experience in Aion Beta. I didn't get to spend much time nor do the traditional 3rd party program, but as you can see from the Macro options, it can be done.

First off let me say I won't be responding immediately as I have some things to do today. Also please refrain from turning this into a flame war.

Introduction: If you don't know what multi boxing is, it's playing 2 or more accounts at the same time. Let me say now that this game is totally set up for multi boxing. First, lets look at the relevant rules regarding game play as it could affect a boxer:

EULA

7. OFFICIAL SERVICE
NC Interactive has designed the Game for official play only as offered through the Service by NC Interactive at the Web Site and not through any other means. You further agree not to access, create or provide any other means through which the Game may be played by others, as through server emulators. You agree not to use any hardware or software, including but not limited to third party tools, or any other method of support which may in any way influence or advantage your use of the Service which is not authorized by NC Interactive, including but not limited to the use of 'bots' and/or any other method by which the Service may be played automatically without human input. You acknowledge that you do not have the right to create, publish, distribute, create derivative works from or use any software programs, utilities, applications, emulators or tools derived from or created for the Game except that you may use the Software to the extent expressly permitted by this Agreement. You may not take any action which imposes an unreasonable or disproportionately large load on our infrastructure.

Rules of Conduct

17. You will not attempt to interfere with, hack into, or decipher any transmissions to or from the servers running Aion.

21. You may not use any third-party program (such as a "bot") in order to automate gameplay functions, including playing, chatting, interacting or gathering items within Aion. You may not assist, relay or store items for other players who are using these processes.

So we see that no 3rd party program that reads packets, automates play without human input, and the gray zone, any method by which the Service may be played automatically without human input. Note that multi boxers press a key for any and all actions, so nothing is automated. The question is will macros that cast more than 1 spell when pressed be considered automation. Another question for other boxers is will key broadcast programs be considered automation. These are the two questions I'd like officially addressed. As it stands boxing is a recognized and legal form of play in many games from L2 to WoW. I would assume this game is no different.

Setup: I have a desktop and a lap top with 2 pre-ordered accounts which gave me double beta access (triple if you include the File Planet access that sucked me right into AION). I had limited time as I work 12 hour graveyards on the weekend and have a girlfriend whom I live with so I didn't get far. I had a warrior and a priest. The war was under my total control with the desktop while the priest was run by 4 macros on the laptop. I had a macro to target and heal the warrior, one for the priest as well, a macro to target the war, her target, then cast smite, wait, cast smite again, and a follow macro. Note everything done was done with ingame tools only. No automation, every command executed when I physically touch a button (the priest macros were bound 1-4 if anyone is curious and that war was run with mouse/n52). The only gray zone is the smite macro, which under the definitions above could be interpreted as automation because more than 1 command is cast at a time. This would make macros useless for pretty much anything though. Still it needs clarity as it's too broad imo.

Play I only got up to lvl 6 and grinded the whole time. Like I said, not much time. The time I did have was a blast. My duo was able to take on mobs 2 levels high than them without much trouble. The macros worked, but they were far from flawless. There is a macro cooldown, I'm guessing of 1 second. The /delay function did not seem to work all that accurately and the /Select targeting didn't work all that great either. Sometimes things went without a hitch, other times I was hitting the macro key 2 or 3 times as it changed targets/skills. It seems that if a macro is running and another macro is called, it will do that change target function of the next macro but not the skill. So if I'm smiting with the priest and the war needs a heal, if that macro is running and I hit the heal macro, I have to hit it twice (with delay for the macro cooldown) to heal. Also my smite command would target the war, then target of target to get the enemy. It seems the macro would target the war if no target was presented, but after that would target of target. This means the first time it would select my wars target, but the next time it would select my war (the targets target). This meant multiple pushes of the attack macro to get the correct target. On the bright side for melee your guys will automaticly chase down the enemy. If I wanted I could have flipped the team and ran my priest while having my war macro attack (basicly just beat things with his auto attack being that I had all of 1 chain skill).

Conclusion Despite the strange actions of the macros which may or may not be ironed out as more people use them and more info is provided, multiboxing is quiet viable and fun. At the same time given the fragile macro system I wouldn't recommend it for anything but grinding. Still this is just one kind of boxing. We don't yet know if the other kinds are legal. For instance key broadcast via hardware/software. If you can press 1 key and have that 1 key count as 1 key press for multiple clients that will open many doors to multiboxers. Oh and if you only have 1 computer, nothing in the rules says alt+tab is illegal so if you ran two clients on 1 PC and manually control both you should be golden. In any case this game is set up quiet well for boxing. I hope It picks up interest among the boxing community as it will probably need all the help it can get seeing how many recent MMOs have risen and fallen.

One last thing. I would still like an iron clad statement from NC. Everything I've seen points to this method being 100% fine, but obviously I don't want to get a ban on the first day. This is a fun game and while I enjoy playing with 2 toons more than 1, I'd settle with 1 if I have to.