[Bane]

I'm sorry but I'm not sure what else you need to know. All you have to do is assign a key to the Voice Message Main command. This is done from MOHAA's options menu.

Voice Message Main may not be the exact name, but it's something similar.

Once you've assigned the key and are in a game press the key. A menu will come up in the middle left of your screen. This is the main menu. Press the number corresponding to the type of message you want and the next menu will come up. Press the number corresponding to the actual message you'd like to say and you'll say it.