So you want to connect to this 'Secret Server' everyone in IRC keeps talking about. Well congradulations you are on the right track.
FIRST you need to let an admin know that you want to connect so we can get you on the Whitelist of the server. Why are we running this Whitelist only? As there is no area protection (to start with) built into the FTB server we are running on the Don't Be A Dick ruleset and need to keep the Griefers away.
Next thing you will need to do is get the special FTB launcher, http://feed-the-beast.com/launcher Upon opening the launcher you will get this screen,
First thing you need to do is select the 'Monster' modpack from the left column, and then change the version to 1.1.2
Once those are selected you will want to click on 'Launch' to initiate the download of the modpack, the game will then launch, most likely go 'Not Responding'' for a little bit and then bring you to the home screen. Close the game at this point we are not quite ready to play yet.
Relaunch the FTB Launcher and once back at the main window, click 'Edit Modpack'
Within this window you will want to add 'BloodMagic' and either 'Zan's Minimap' or 'REI Minimap' to the enabled mods list by selecting them and clicking 'Enable'
Once added, close the window.
The last thing to do before getting into the game is upping the amount of RAM available to FTB. Click on the 'Options' tab at the top of the launcher. Then increase the amount of available RAM.
Once in the game, just add the server as you would normally.
Now click Join Server and WELCOME to the WORLD, ask around if you have any questions!