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. Type M-x slime-connect and you'll be prompted for a host (use the default, which is 127.0.0.1) and then a port. The port needs to match the port (default 4005) that was printed out earlier.
You are now connected to Opusmodus. You should be able to say stuff like (list-plot '(1 2 3)) from the SLIME repl and have it work.
The function cl-user::start-swank basically does (load "home:quicklisp;setup") and then (ql:quickload :swank) and then (swank:create-server :port 4005 :dont-close t), so there's no magic going on there.
If you run into trouble, let me know and I'll try to help out.