First Time doing this? Look below. (There is a separate one for others who have done this before now, just look further down).
1. If you have not yet downloaded the launcher for FTB, download it here.
2. Open the launcher, go to the options tab and make sure you have at minimum 2GB of RAM allocated to FTB. You shouldn’t need to use more than 4GB.
3. Go back to the FTB Modpack tab (when you open the launcher it goes here by default), find the FTB Infinity 1.7 and make sure it is selected. Now look beside “Download Server” and there should be a button you can press that says “Recommended”. Clicking this will bring down a list of other possible versions, select 1.11.2
4. Click launch and wait for the game to boot up. Once it has finally booted up, quit the game.
5. Now find where all of the files have downloaded and installed to.
A quick easy way to do this is either:
a.
Open up the launcher.
Click the options tab
Where it says “Install folder” will be where the files have been installed to.
Follow the pathing to get to the files.
or
b.
Open up the launcher.
Make sure you have FTB Infinity 1.7 selected and click “Edit Mod Pack” it is right beside the “Download Server” button.
After you click the “Edit Mod Pack” Button a new tab will pop up and at the bottom left corner it says “Open Folder”.
Click it and it will take you straight to the mods folder for FTB Infinity.
At the top it the pathing should be something like:
FTB -> FTBInfinity -> minecraft -> mods
Click minecraft and it will take you to the rest of the files you’ve downloaded.
6. Download [size=1em]this file.
In the FTB Infinity minecraft folder (the files you downloaded), delete these folders: Configs, Mods.
Now from the files you just downloaded, drag and drop the new Configs and Mods folder into the same place where the originals were.
7. Exit out and boot up the launcher. Click launch and wait for minecraft to boot up. If it boots up properly, you’ve got it!
8. Click multiplayer and add in the server IP 63.141.245.210:25533 and then join the server and play!
If you have any questions or issues please feel free to post below or bug myself, Crass, or Kyle. (You can probably ask Fatso to, I’m sure he wouldn’t mind).
[b]Done this before? Look here.
1.[/b] Open up the launcher. Go to the options Tab, click “Force Update.” Now go back over to the mod pack list. Change the version you have of Infinity to 1.11.2, then click launch. Once it finishes downloading and boots up to the title screen, close minecraft.
2. Download the Mods and Configs here. Swap out the the Mods and Configs folder in FTB with the ones that were provided in this step. (If you forget how to do this read step 5). Then open up the launcher and click launch.
3. You should be ready to play FTB again, have fun! 
I love Hexxit, so FTB will be just as awesome. Even more awesome with this epic community!