I use 3 physical machines to box like that. It wouldn't work on one box because the EQ client is so old that it gets user input in some archaic way which does not allow for the sending of input to background windows. If you use boxing or macro software, you have to tell the OS to bring the window you want to send input to into focus first before sending commands, and then wait again after sending a command before bringing another window to focus. These delays are significant enough that they would cause delays prior to casting color stuns. Even my using 3 physical machines instead of giving enchanters dedicated boxes makes it slightly more dangerous.
You might get around that limitation by using VMs for every client, but that would be a huge PITA and difficult to setup at the very least. Also this client does not play well with other clients on the same processor core, as the game uses up the entire core no matter what is on screen or where you are, because back then the game was assumed to be the only thing running on the machine (it disabled alt-tab even) so they didn't concern themselves with resource usage. (that and Sony's coders weren't in Blizzard's league, sorry to say) As far as I can tell, EQ is extremely CPU limited, and all the frame lag is from that and not slow GPUs.
I saw that Zamiel made some sort of macintosh multi-client manger software that probably makes boxing on macs a better experience now.