In your script, press Ctrl+K then the number for the colour you want, then the text that you want coloured.
You can also put the colour number into a variable (%colour in the folowing example) and then use something like
msg $chan $+($chr(3),%colour) text
$chr(3) is the equivalent of pressing Ctrl+k in mIRC
Thus a script might look like
on *:text:Hi*:#:{
if $me isin $2- {
var %colour = $r(0,16)
%colour = $iif(%colour == 16,99,%colour)
.msg $chan $+($chr(3),%colour) Hi $nick
}
}
As mIRC has 16 colours in it's colour pallette (numbered 0 to 15), I add an extra number (16) then check to see if the random colour number matches 16, and if it does, I set it to 99, which always returns the system default colour.
Note that some people might not be able to see/read the reply easily, as there's a chance that your reply colour matches their background colour or that it is very close (eg: yellow on white is hard to read for most people)