you don't have to, use alt O > IRC > Highlight, click on add , then just add $me to the list choose the colour, but i think thatl highlights the whole line. otherwise you would need to use an on ^*:text and use $reptok or $replace to replace your nick with a coloured one.
^ halts the default echo, read /help halting default text for more info this will only replace if your nick is a whole word, might want to think about removing other colour codes for the reptok, if there when in the same would as your nick then you would wouldnt be shown red. try this:
