elisp code to ease firing off my local pjs-enabled builds of firefox using an isolated profile (and thus be able to run it in parallel with my main Firefox instance).

gistfile1.txt

(defun gud-pjs (command-line)
  "Wrapper around gud-gdb that runs firefox using my pjs-alpha profile."
  ;; --P pjs-alpha
  (interactive (list (gud-query-cmdline 'gud-gdb)))
  (let ((new-command-line
         (cond ((string-match " --args " command-line)
                (concat command-line " --P pjs-alpha"))
               (t
                (concat command-line " --args firefox --P pjs-alpha")))))
    (gud-gdb new-command-line)))