This has been brought up in the past but I think that it's best a new thread is created for it.
It is really a pain to have a text and input event just to change the way mIRC displays the nick. You'd also have to rewrite the /msg command so that your messages from scripts also follow the same format or message using /editbox -n to activate the input event which is more trouble than it's worth.
/nickstamp seems logical and I doubt it would be a hassle.
p could equal prefix
c could equal nick color
n could equal nick
So currently, assuming show user prefix and nick colors are set, our nickstamp format is
Being able to customize that would be pretty cool :P