how to highlight fine differences in Diff mode?

[Kevin Rodgers <ihs_4664@yahoo.com>]

I love Ediff.  I mean, I really, really love it.

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?

-- 
Kevin Rodgers