You should be able to do this, I think you're encountering a quoting/spacing issue in your definition of the command `sudoedit /path/to/file`.

For starters I'd try just this:

    john ALL=(ALL) NOPASSWD: /usr/bin/sudoedit

If this works then I'd try to this:

    john ALL=(ALL) NOPASSWD: "/usr/bin/sudoedit /path/to/file"