Download the latest version of MultiMC: http://www.minecraftforum.net/topic/1000645-multimc-42-windows-linux-mac/ Run MultiMC. Click on the drop down arrow to the right of "New Instance" Select "Import from FTB Launcher" Find the folder that has your FTB launcher exe in it and click select folder. Select FTBBETA from the "Select FTB pack to import" dialogue box and click ok. Name the instance(doesn't matter whatcha name it). It will discover and copy the files, so for now just wait. Right click on your new instance and click play. Put in your username and password for Minecraft, then click ok. MultiMC should do everything else for you. Play FTB! Note: This requires you to already have FTB installed. If you do not have the FTB launcher downloaded already, this will not work for you.