There is currently a port of Quicklisp (client code) to MKCL in progress on github.
You could start using it if you are somewhat adventurous.

First, clean-up your ~/quicklisp directory (ie: rm -rf ~/quicklisp, or mv ~/quicklisp ~/quicklisp.keep, or ...).

Then clone the two small github repositories by doing:

git clone git://github.com/jcbeaudoin/quicklisp-bootstrap.git ~/quicklisp
git clone git://github.com/jcbeaudoin/quicklisp-client.git ~/quicklisp/quicklisp

Now you can start your mkcl and do this to load the quicklisp client:

(load "~/quicklisp/setup.lisp")

On first attempt it may take a while to get a prompt back since quicklisp/setup.lisp
will do a compilation of the whole quicklisp client code. It's much faster later on.

Since you're getting this from mkcl-devel you should consider this code as
experimental alpha quality at best.

Enjoy, and bug reports are most welcome.

Jean-Claude