Something

from django.conf import settings
from django.conf.urls.defaults import *
from django.views.static import serve

urlpatterns = patterns('',

    [your normal url config]

)

if settings.DEBUG:
    urlpatterns += patterns('', 
        (r'^m/(?P<path>.*)$', 'django.views.static.serve', {'document_root' : '/some/path/to/project/media'}),
    )


*** alternatively you can just do ***

urlpatterns = patterns('',
    (r'^css/(?P<path>.*)$', 'django.views.static.serve', {'document_root' : '/some/path/to/project/media/css'}),
    [your normal url config]

)