Presume you can talk to remote-host through ssh.

Install slime in ~/slime/ on both remote-host and the local host.

Create a file ~/swank.lisp on remote-host with the following lines:

(load "~/slime/swank-loader")
(flet ((create-server-aux ()
             (swank:create-server :port 14005 :style :spawn)))
  (swank::initialize-multiprocessing #'create-server-aux))

;; now the ssh command from emacs is: 
;; M-x ssh RET remote-host -L4005:localhost:14005 bash --login -c "lispworks -init swank" RET

Then you can say the following in the local XEmacs:

M-x slime-connect RET RET

Or merge the two into the following emacs lisp function:

(defun slime-on (host)
  (interactive "sHost: ")
  (let ((bufname (generate-new-buffer-name (format " *swank-init@%s*" host))))
    (ssh (format "%s -L4005:localhost:14005 bash  --login -c \"lispworks -init swank\""
           host)
     bufname)
    (accept-process-output (get-buffer-process bufname))  
    (slime-connect "localhost" 4005)))