So in your example if you media directory was /var/www/ you have in
your urls (r'^site_media/(?P<path>.*)$', 'django.views.static.serve',
{'document_root': '/var/www'}),
You then add your admin media to that directory so if you are using
media for your admin media all of contrib/admin/media should be in
/var/www/media.
From here you add your js for tinymce so the path would be from your
example /var/www/media/js/tiny_mce/tiny_mce.js and
/var/www/media/js/tiny_mce/textareas.js
Just as a best practice I wouldn't put the tinymce script into my
admin media area because that is liable to be updated and you don't
want to acciddentally overwrite "core" javascript. If you follow the
example it has you putting the scripts into other folders.
Hope that helps,
Michael