I too am running SME 5.0 with Update 3. I downloaded the 21 files from
ftp://ftp.e-smith.org/pub/e-smith/updates/5.0/Update4/RPMS/ and ran "rpm -Uvh *.rpm" just like the README said. I got errors about failed dependencies similar to what Ille mentioned. Other than the Blades for Updates 2 and 3, the only things I've installed are the User-Manager and Port Forwarding panels.
error: failed dependencies:
php = 4.0.4pl1-9 is needed by php-manual-4.0.4pl1-9
warning: LOOP:
warning: removing e-smith-base-4.6.1-21 "Requires: e-smith-lib >= 1.6.0" from tsort relations.
warning: e-smith-base-4.6.1-21 Requires: e-smith-lib >= 1.6.0
warning: removing e-smith-lib-1.6.0-11 "Requires: e-smith-base >= 4.6.0" from tsort relations.
warning: e-smith-lib-1.6.0-11 Requires: e-smith-base >= 4.6.0