If I were you I would make the changes to the package directly in the checkout of that package. You could do
cd /web/openacs-dev/packages
cvs -d :pserver... checkout -d package_name openacs-4/packages/package_name
to get the package sources into your dev source tree. If you want both local revision control and updates from openacs.org there is a way to do that as well. I think it's described in Andrew Grumet's CVS document (and in other documents) linked here:
http://www.piskorski.com/docs/cvs-conventions.html
