I did this recently for a UP player. If you look at NUS it all ready has that built in.
It's set up so you can have 4 say lines by hitting the 1-4 buttons on the keypad on the right of your keyboard, or 4 say team or you can mix and match them. All you have to do is click on the shortcut to it that is made in your start/programmes menu and type in what you want to say. If you wanted to make your own one that just did say commands you would have to set it up in your autoexec.cfg file.
In the file it would look something like this. The parts in green are where you would type your words. In NUS it looks even simpler than this;
unbind KP_END //keypad button 1
unbind KP_DOWNARROW //keypad button 2
unbind KP_PGDN //keypad button 3
unbind KP_LEFTARROW //keypad button 4
bind "KP_END" "m1"
bind "KP_DOWNARROW" "m2"
bind "KP_PGDN" "m3"
bind "KP_LEFTARROW" "m4"
alias m1 "say message 1"
alias m2 "say message 2"
alias m3 "say message 3"
alias m4 "say message 4"