FTPii doesn't work like that. You connect to it, you cannot have it connect to another source. If you want linux you would still have to get the files on your computer so that you can get the files ready for install. If you want a way to download homebrew to the wii use the homebrew browser. By dangerous homebrew I guessing you mean something that isn't supported here. It is just impractical, and not a worthwile idea.