Say you're working on a Debian box for which you don't have root access, you
need to get some source packages, but there is no
(or not the ones you need) in
/etc/apt/sources.list. So usually
you will have to manually wget the files, after looking the exact location, and
all that jazz.
Today I found that APT can be configured to use a different
sources.list file, and different directories for the package
lists. Which is enough to make it work for downloading source packages.
What you need to do is:
$ mkdir apt
$ cp /etc/apt/sources.list apt/
$ vi apt/sources.list # customise as needed
$ mkdir -p apt/lists/partial
$ cat > apt/apt.conf
Dir::Etc::SourceList "home_dir/apt/sources.list"; # You need to use the full path
$ export APT_CONFIG=~/apt/apt.conf
$ apt-get update
$ apt-get source foo
After downloading the lists, it will complain about it not being able to lock the dpkg directory, but no need to worry. It will work perfectly.