If you want to use Emacs and SLIME with Opusmodus, that is possible.   Here are steps that work: If you haven't already done so, install Quicklisp. Evaluate (ql:quickload "quicklisp-slime-helper"). Follow its instructions and put (load (expand-file-name "~/quicklisp/slime-helper.el")) into your ~/.emacs file. Start Opusmodus, and evaluate (cl-user::start-swank). This should print something like ";; Swank started at port: 4005". Now, start your Emacs.  Ty