Could not find this command so its here for the zeitgeist!
"C:\Program Files (x86)\Microsoft Expression\Web 4\XSetup.exe" -r -AppLangId:1033 "-manifest:WebManifest.cab" "
-source:C:\Program Files (x86)\Microsoft Expression\Web 4\Setup\;g:\6cf48c91055c9ced0efc944087\Setup"