Create a file named emdiff somewhere in $PATH with the following and make it executable

#!/bin/bash
emacs -nw --eval "(ediff-files \"$1\" \"$2\")"

Add this to ~/.emacs to make ediff work side by side
(setq ediff-split-window-function 'split-window-horizontally)

For git, use
git difftool --extcmd=emdiff

Finally
echo "alias gitemdiff='git difftool --extcmd=emdiff'" >> ~/.bashrc