VC via tramp without vcdiff

[Yary Hluchan]

I'm editing files under revision control (plain SCCS) on a remote
host, using tramp. The remote host doesn't have an implementation of
vcdiff, nor does it have any c-compiler with which I can build an open-
source vcdiff implementation. Emacs wants to run vcdiff with every
check-in and when that fails, VC fails.

Can I tell Emacs/tramp to use "sccs diffs" instead of "vcdiff" for
sccs (or even for everything)?

Even if I could find a perl vcdiff or a pre-compiled vcdiff, I'm not
sure I have permission to put it in a place where emacs could find it
on that system, or how to tell tramp to add to its $PATH.