code walker -- ticl::let-if

[goldman@vaxa.isi.edu]

The TI explorer common lisp has a macro IGNORE-ERRORS whose macro expansion
involves a ti special form called TICL::LET-IF.  This causes the PCL code
walker to die, [without even the right error message, because 
(fboundp 'ticl::let-if) is true, and PCL's code walker does not catch
alien special forms if they are fboundp.  Although it seems strange
for a special form to be fboundp, apparently it can make sense in ti
common lisp because there is yet another extension to CL, &quote as
a lambda list keyword!]

Does anyone have a proper extension for the PCL code walker to handle 
TICL:LET-IF?

neil