I have not been able to get text colors to work using the alias command in-game, but - I was able to get them to work if I manually change the layout file. Here are some examples (for red, blue, green, and yellow text), hope they help:

<Aliases>
<Alias String=";b" Value="&lt;rgb=#00aaff>B&lt;/rgb>"/>
<Alias String=";g" Value="&lt;rgb=#00ff00>G&lt;/rgb>"/>
<Alias String=";r" Value="&lt;rgb=#ff0000>R&lt;/rgb>"/>
<Alias String=";y" Value="&lt;rgb=#ffff00>Y&lt;/rgb>"/>
</Aliases>