plediii

(defun prepend-to-path (&rest paths)
  (map 'nil (lambda (path)
	      (let ((old-paths (getenv "PATH")))
		(if (and old-paths (not (equal old-paths "")))
		    (if (not (member path (split-string old-paths ":")))
			(setenv "PATH" (concat path ":" old-paths)))
		  (setenv "PATH" path)))
	      (if (not (member path exec-path))
		  (setq exec-path (cons path exec-path))))
       (reverse (prune-directory-list paths)))