Nevermind what used to be in this post, here is an updated version of Monster.ini, with the Neptune boss alarm. This one announces their name and potency, so you don't look like a complete cheater when you rush out to kill Dun_B_TopRoom. Thanks to chongkhb for helping me confirm that I did everything right.
Oh, and before I forget, no thanks at all to the beggy noobs that just wanted someone to do this. You all can rot.
This is here because I don't believe in deleting parts of posts when I edit them. Ignore it
Yes, this is almost exactly what you think.
I don't actually have the monster.ini with the alarm, but I've seen the alarm code. Aside from the Neptune bosses, there are a few monsters that I'm interested in actually seeing, because I've never even heard of them before. I copy/pasted the alarm code for the GPA boss into another monster, but it only half works. What I mean is that I can get the system message to announce that the monster has spawned, but all it reads is "Dun_A_TopRight!", or whatever equivalent. No monster name, no coordinates, no "Alliance members, pay attention". I've gone a few threads back and know that asking for monster.ini doesn't really get results, but can someone at least help me with this?