You mean attach the ever-changing colored nick to the end of your message sentence? If not, give an example of what you want.
You can't change nick to be a 24-bit color, the best you'll be able to do is use one of the color index numbers in the alt+K window. Note that 16-98 would either be those colors or would be color(normal) for older clients not supporting that. But index 0-15 can be changed by anyone to match their own background.
Choosing colors to send inside a channel text message is difficult, because unless you specify a background color for that line, there's very few colors that work well against both black/white backgrounds. i.e. try the default blue with a black background or default yellow with a white background.
