You can add new ways of making existing definitions and use the dspec system to track these definitions. This is what happens when your defining form expands into a system-provided form. The macro define-dspec-alias is used to inform the dspec system of this.
For example if your definer is:
(defmacro my-defun ((name &rest args) &body body)
`(defun ,name ,args ,@body))
then you would define the form of dspecs for
my-defun
definitions like this:
(dspec:define-dspec-alias my-defun (name)
`(defun ,name))
Note: in general you should not include the lambda list in the dspec, because it is not needed to locate the definition later.
Note: to make source location work you will also need a define-form-parser definition for my-defun. This is illustrated in Using pre-defined form parsers.
LispWorks User Guide and Reference Manual - 21 Dec 2011