Here is what I've come up with for the install-info example.
Let me know if problems.
do-install-info: foo.info
$(NORMAL_INSTALL)
# There may be a newer info file in . than in srcdir.
-if test -f foo.info; then d=.; \
else d=$(srcdir); fi
$(INSTALL_DATA) $$d/foo.info \
$(DESTDIR)$(infodir)/foo.info
# Run install-info only if it exists.
# Use `if' instead of just prepending `-' to the
# line so we notice real errors from install-info.
# Use `$(SHELL) -c' because some shells do not
# fail gracefully when there is an unknown command.
$(POST_INSTALL)
if $(SHELL) -c 'install-info --version' \
>/dev/null 2>&1; then \
install-info --dir-file=$(DESTDIR)$(infodir)/dir \
$(DESTDIR)$(infodir)/foo.info; \
else true; fi
