Similarly to the Cogvm package I setup a system to generate a .deb for the sources files and installed it on box4. All of the sources are extracted in and can be linked to from /usr/lib/squeak/sources/. Whenever possible please link to these rather than have your own copy taking up more space on the filesystem.
The .deb can be found at
/root/localdebs/squeak-sources_4.1-1_all.deb
and the build 'system' at
/root/localbuild/squeak-sourcesdeb.zip