Make emacs load .spkg files like .tar.gz files

Add the following to your .emacs:

;; the following makes .spkg files load automatically
(add-to-list 'jka-compr-compression-info-list
'["\\.spkg" "" "" nil "unspkging" "bunzip2" ("-c" "-d") t nil "BZh"])
(jka-compr-update)
(add-to-list 'auto-mode-alist '("\\.spkg$" . tar-mode))