Here is a link to the Terrain Add-In that can be downloaded from rapidshare. It is (unfortunately) in two parts because of the 100MB rapidshare limit (file is 107 MB). Download both parts to the same location. You will need to open up the extraction utility then select the first file (Tonnage War Mod v1.03 Terrain Add-In.7z.001) and extract as normal, or combine the files and extract.
http://rapidshare.de/files/16676804/...In.7z.001.html
http://rapidshare.de/files/16678223/...In.7z.002.html