RE: how to highlight fine differences in Diff mode?

[Drew Adams]

    But sometimes I have to compare extremely large files, larger than Emacs
    maximum buffer size.  So I simply run diff and redirect its output to a
    .diff file, which is easily small enought to visit and navigate in Diff
    mode.  What I'd like at that point is a command to highlight the changed
    text within the current hunk, just like "*" does in Ediff:

    ,----[ C-h k * ]
    | * runs the command ediff-make-or-kill-fine-diffs
    |    which is an interactive compiled Lisp function in `ediff-util'.
    | (ediff-make-or-kill-fine-diffs ARG)
    |
    | Compute fine diffs.  With negative prefix arg, kill fine diffs.
    | In both cases, operates on the current difference region.
    `----

    Is there any way to take advantage of the Ediff machinery inside
    Diff mode?

I don't have an answer for you, unfortunately. I do have some code that
improves the highlighting of regular `diff' output slightly:
http://www.emacswiki.org/cgi-bin/wiki/diff-mode-.el, but it doesn't do what
you're asking.