Don't know how those work, I'm not even sure they use the same framework as what most add-on use, but I'm pretty sure you could just fetch some data in the computer's memory to get camera position, angle etc. so that you can use another software to draw AoEs and whatnot. Pretty sure that's what being done already, too.
It's not like mods, where you, as far as I know, actually change some data in the game files (or at least redirect them), because in that case, you just need to read your own VRAM/RAM, so yeah, you can't do that serverside unless you actually scan the computer itself.
