But in all seriousness, people don't notice the message even when it's in plain sight like that, which is why the popup would help, imo. There will still be a few idiots that ignore the message, but whatever.
Either that or make a bunch of arrows that point to the dialogue box that already exists
It is possible but only for someone who doesn't mind trawling through xenforo's code and make some custom modifications. There are much more important things for the very few people who program for the site to do, unfortunately.