Find a Text File in one of the Red Faction VPP files from the Single player maps using the VPP builder to extract it. It must be a Text file containing the messages from the single player game.
Use the text file as a template for your messages, except change the messages to something you want.
When you link a trigger to the "Messeage" event, the event has got to read from the Text file of the number of that message...
Example, you have a message ID 8 and your event is set with ID 8, the event reads for that part of the text and displays it.