[asdf-devel] loading a standalone lisp file

Hi, If I have an ASDF system that :depends-on various other ones _and_ some other library that does not have and .asd file (eg it is a standalone .lisp file), what is the standard way of loading the latter? I am looking for something that eg automates manually executing (load (compile-file "/path/foo.lisp")) and how to incorporate this into a defsystem. Thanks, Tamas