User Feedback :: Out of space
It's not too late to do it from bootlocal.
Are you running frugal or a traditional harddrive install? I ask this because in frugal the /usr file is a symlink that is less likely to cause unexpected trouble when removed. I assume you have a traditional harddrive install.
In traditional harddrive install, delete the *contents* of /usr and mount /dev/hda3 to /usr
In frugal, delete /usr, mkdir /usr, and mount /dev/hda3 to /usr. Don't bother auto-loading *.dsl extensions if you do this; they will be deleted.
This must be done as root, before dsl logs in. It could be done before bootlocal, but i feel bootlocal is just the most convenient place.
Problem solved. The mountall script in init.d contained an # in the first line. 
Whoops!
original here.