http://gothub.r4focoma7gu2zdwwcjjad47ysxt634lg73sxmdbkdozanwqslho5ohyd.onion/gorilla-devs/ferium
Now after adding your modpack, run ferium modpack upgrade to download the modpack to your output directory.
This defaults to .minecraft , which is the default Minecraft resources directory. You don't need to worry about this if you play with Mojang's launcher and use the default resources directory.