swank-clojure 1.2.0 made the setup process much less painful. Yes, you still need to install Leiningen and Emacs manually. After that, (1) an experienced Emacs user can install clojure-mode and SLIME manually, or (2) anyone can use ELPA to install those two modes. Those are fairly easy tasks, and don't require much tweaking.

swank-clojure 1.2.0, which was always the hardest part, does not need to be installed manually. It just gets listed as a dependency in project.clj, and after that "lein swank" on the command line does magic.