So no portfowarding and the one hosting the lan server is only required to download this?
That has nothing to do with port-forwarding, it just allows you to set a custom port and MOTD instead of Minecraft generating them randomly. So for example, you might port forward a certain port, but don't want to keep port-forwarding another one each time you launch a LAN server, you can use this mod to allow you to set the port to the one you port-forwarded. And MOTD is simply the text that appears under your server on a server list.
I just installed this, and it works great. Finally my roommate can save Waypoints from Rei's Minimap when he joins. A comment on the MOTD though, it doesn't seem to allow the Entities Radar function to work. Is this a true MOTD, or just a description under the LAN Server?
I don't think entity radars work in SMP, believe me, I've tried.