This page is full of helpful stuff.

 

See all the chat channels at once
Cant read what people are saying on @Clan channel when in a party and #Party when on @Clan channel?

It opens this toggle box. Select the important ones, and include Alliance if we're that brilliant by the time your reading this. Do this with each channel individually.

Now you can read all channels at once. Remember to get the prefix's (@, # etc) right to avoid embarrassing cross chats!