How are the messages sent to the terminal? Do you run a program that outputs them, or is the server sending them to all terminals with something like wall?

The first case is simple: pipe the output of the program to a script which does what you want with the output while reprinting it verbatim to the screen. The second case (which I'm guessing fits here) is more complicated, and depends on whether you're running this eterm on the server and displaying it on your local machine, or running the eterm on your local machine and connecting to the server with something like ssh. There may also be a better way to do it.