(defmacro defclient-callback (name args &body body)
  `(defmacro ,name ()
     (<:as-is
      (js:js*
       `(defun ,,name ,,args
	  ,,@body)))))

(defclient-callback client-callback1 (event)
  (alert "client-callback1 is called."))

expansion of client-callback1:
(DEFMACRO CLIENT-CALLBACK1 ()
  (IT.BESE.YACLML.TAGS:AS-IS
   (JS*
    `(DEFUN ,CLIENT-CALLBACK1 ,(EVENT)
       ,(ALERT "client-callback1 is called.")))))