I've had a Party for years, but never got around to doing this mod. I have the expanded metal for it in the shed. If I ever decide I need to spend the time on this mod, i would just make expanded metal walls on all four sides of the basket, leaving them a couple inches under the deflector plate. I would bolt them to the existing walls of the charcoal pan, or have a buddy weld them on. I would also cut out an access opening on the front side of the pan for adding fuel during the cook.
Or you could do a search on the backwoods website forums and see what others have done. I know Ive seen pictures over there before.