Unfortunately what you are looking for is not entirely possible with Lua. You can read from the chat channels with the API, but it doesn't give you access to things such as the game settings. It is possible to make a plugin with its own chat window and customised colour settings for each channel - but as you're unable to post from the plugin, it would be a bit pointless. Most plugins use the chat API for reading things such as quest updates, or combat logs, to do something else within the plugin.
Galuhad | Narvelan
Lore Breakers of Eldar