Hi Erick
try micetek.com(formerly microtek).
they are the manufacturers of microtek series ICE. sometime back i happened to talk their ICE designer and he was mentioning they were using Winbond chips for their EasyPack series 8052 ICE. i don't know how much it is useful to you. you can always check with them.
if you are interested pls contact me and
i will pass you the designer's e-mail address.