I’m using it with VIM mode. Basically ESC-v (or simply v if already in command mode) opens the terminal. It is setup by:
autoload -U edit-command-line
zle -N edit-command-line
bindkey -M vicmd v edit-command-line
Here is how to setup it in emacs mode:
autoload edit-command-line
zle -N edit-command-line
bindkey '^Xe' edit-command-line
Use ‘bindkey -e’ to to enable emacs style or ‘bindkey -v’ to enable vi style.