With a Lisp implementation that can be started from the command-line, installation just requires a few lines in your ~/.emacs:
(setq inferior-lisp-program "the path to your Lisp system")
(add-to-list 'load-path "the path of your slime directory")
(require 'slime)
(slime-setup)
We recommend not loading the ILISP package into Emacs if you intend to use SLIME. Doing so will add a lot of extra bindings to the keymap for Lisp source files that may be confusing and may not work correctly for a Lisp process started by SLIME.