(unwind-protect
    (when (load "tramp" t)
(defvar find-file-root-method "sudo:"
  "*The Tramp method to use for opening files with `find-file-root'.")
(defvar find-file-root-user   "root"
  "*The user to su to when opening files with `find-file-root'.")

(defun find-file-root (file)
  "Open FILE sued to a different user.
  Uses the method specified in `find-file-root-method' and the user from
  `find-file-root-user'."
  (interactive "FFind file (as UID 0): ")
  (require 'tramp)
  (find-file (concat "/" find-file-root-method find-file-root-user "@localhost:" file)))

(global-set-key [(control x) (control r)] 'find-file-root)))