there are a lot of way, you can try colouring part by part... for example
on the conversation window
/nick ·$1 MaRio·$5 is the best ·$21 here...
this i gonna give is the nick on three different color, "mario" with a color, "is the best" with another color, "here" with another color
uses ( ·$ ) on the preferences of the MSN to change your nick, you can try some Hexadecimal colors...
like this ones:
http://www.webtaller.com/utilidades/csscoder/colores.php
just copy the code of the color ( like this #0099FF ) and put it after ·$ and then put your nick
example:
·$#0099FF Mario·$#FF0000 likes ·$#00CC00Final Fantasy VII
just put ·$ and the hexadecimal code for every part...