Implementing :TEMPORARY hash tables at the Lisp level?

["Steve Bacher (Batchman)" <SEB1525@draper.com>]

Just a question.  If one were to implement :TEMPORARY hash tables as
described - i.e. testing to see if the test were #'EQ or #'EQL - well,
just how does one code such a test in CL?  Presumably you'd have code like
  
 (case test 
       ((#'eq #'eql) (make-em-collectible))
       ((#'equal)    (dont-make-em-collectible))
       (otherwise    (make-em-whatever-you-want)))
  
But... there is no way of testing equality of functions, lexical closures,
or what have you, in CL.  So how can this possibly be implemented?