If you use Windower, there are also publicly available (i.e., directly obtainaible from the Windower forum) aliasing scripts that will let you "bind" Alliance targeting to new hotkeys ... much like single-party targeting is already set to keys F1 though F6.
You could set everyone in Party #2 to be targeted with Ctrl+F1-F6, for example, and everyone in Party #3 to be target with Alt+F1-F6. In that way, you could easily be able to quickly target all 18 people with the same six set of keys.
I also have to agree with others about the usefulness of being familiar with typed commands. I can't even tell you how much I rely on /ma "Spell Name" (target). I can't be arsed to make a REAL macro for every spell and/or situation in the world (I'm not going to make a macro just for Warp, for example) ... if you can type quickly enough, it can generally actually be FASTER to manually key in "/ma 'Warp' <me>" than it would be to tab through four macro sets, find a pre-set macro, sit through server lag, and finally watch the command go through.