NOTE: The path that I speak of starts at the directory of which your FTB launcher sits in. Some may have a different path setup initially here, so keep that in mind when I speak of the "FeedTheBeast" directory.
1) Navigate to *\FeedTheBeast\Earf2\minecraft.
2) Delete or rename the directory "mods" and the directory "config" in this folder.
3) Download THIS
4) Extract it on your desktop or wherever you want
5) Move the mods and config folders from the extraction to the minecraft folder you still have open (see step 1)
6) You should now have a mods and config folder sitting in the same folder as the rest of your minecraft stuff--such as your save folder, log files, settings files, etc. If they don't appear in this directory, you may have placed them inside of another directory within the minecraft folder; correct this.
You should now be able to join the server. Happy tree punching :).