UFFI-izing some CLisp FFI

I have some CLisp with native FFI I am trying to switch to UFFI. Ran 
into some stuff which is over my head. Here is the CLisp:

(defun gtk-object-set-property (obj property val-type val)
  (let ((varargs-def
     `(c-struct list
       (value ,val-type)
       (end c-pointer))))
    (with-c-var (vec varargs-def (list val nil))
      (g-object-set-valist obj property
             (c-var-address (slot vec 'value))))))

I see UFFI has with-foreign-object to replace with-c-var (right?), but 
that does not take optional initialization. OK, I just do the 
initialization procedurally in the body? I'll live.

And that type-on-the-fly `(c-struct list ...) -- no can do in UFFI, I 
think. I need to break that out as a standalone:

   (uffi:defstruct valist..)?

How'm I doing?

kt

-- 
Cells? Cello? Celtik?: http://www.common-lisp.net/project/cells/
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-- 
Cells? Cello? Celtik?: http://www.common-lisp.net/project/cells/
Why Lisp? http://alu.cliki.net/RtL%20Highlight%20Film