You can't use the Address book's 'Colors' tab, but you can use the Options/IRC/Highlight stuff.
This can match text strings, and highlights (or plays a sound or ... etc.) based on the plain text string you've entered.
For example, I highlight '*bek*' to higlight lines with a partial-match of my nick in it.
It is not something that I write, it is something that the others write.
