(setq el-get-sources
      '((:name session :url "http://downloads.sourceforge.net/project/emacs-session/session/2.1c/session-2.1c.tar.gz")))
(el-get 'sync "session")

(setq el-get-sources
      '((:name session :url "http://downloads.sourceforge.net/project/emacs-session/session/session-2.3a.tar.gz")))
(el-get-update "session")