So, in case no multiple emails were sent, he has a file that looks like:
(ql:quickload #:foo) (in-package #:foo)
(asdf:load-system #:bar) (in-package #:bar)
and so on.
Hi!
I have no solution for you, just some ideas.
There is slime-enable-evaluate-in-emacs variable in SLIME. Docstring states "*If non-nil, the inferior Lisp can evaluate arbitrary forms in Emacs. The default is nil, as this feature can be a security risk".
Also (swank-repl::repl-eval "(in-package :cl-user)") _might_ help you. I don't know if you need to enable this variable.
Look for "current lisp package" words in slime.el and read the comment there.
It seems that SLIME already tries to deduce current package for the point in the file from nearest previous in-package form. Simple experimenting should show. I'm not a EMACS user, so I can't help.