defmacro lambda lists, function arglist

How can I get Lispworks to remember the lambda lists of defmacros?
For instance, if I run "Function Arglist" on when-let (in package cl, of course)
I get "The lambda list of the macro When-Let is ((Variable Form) &Body
Body)" in the
minibuffer. Wonderful. 

Say I was to define if-let:
(defmacro if-let ((var form) if-stmt else-stmt)
     "like when-let, but with an else clause"
    `(let ((,var ,form))
       (if ,var
         ,if-stmt
         ,else-stmt)))

now, "Function Arglist" on if-let
"The lambda list of the macro If-Let is (%%Macroarg%% &Environment6149)"
which is nowhere near as useful...

How can I preserve this information? It sticks around for normal functions
and method.. In MCL is was as simple as 
(setf ccl:*save-local-symbols* t)
in the initialization file.. What do I need to do for Lispworks?

=====================
Joshua Taylor
tayloj@rpi.edu