Fetch feeds requiring authentication

[willow]

I want to fetch some feeds which requires authentication such as gmail. If fetching it directly, it will say so:

Traceback (most recent call last):
File "/Applications/calibre.app/Contents/Resources/lib/python2.5/site-packages.zip/calibre/parallel.py", line 760, in worker
result = work(client_socket, func, args, kwdargs)
File "/Applications/calibre.app/Contents/Resources/lib/python2.5/site-packages.zip/calibre/parallel.py", line 729, in work
res = func(*args, **kargs)
File "/Applications/calibre.app/Contents/Resources/lib/python2.5/site-packages.zip/calibre/ebooks/lrf/feeds/convert_from.py", line 42, in main
recipe = run_recipe(opts, recipe_arg, parser, notification=notification, handler=handler)
File "/Applications/calibre.app/Contents/Resources/lib/python2.5/site-packages.zip/calibre/web/feeds/main.py", line 114, in run_recipe
recipe.download()
File "calibre/web/feeds/news.pyo", line 473, in download
File "calibre/web/feeds/news.pyo", line 586, in build_index
File "calibre/web/feeds/news.pyo", line 781, in parse_feeds
File "mechanize/_mechanize.pyo", line 203, in open
File "mechanize/_mechanize.pyo", line 254, in _mech_open
httperror_seek_wrapper: HTTP Error 401: Unauthorized

Since I don't know how to use the advanced mode, it is a little hard for me to solve it, will anyone help me?