Not cheats
Sorry Pokemaster, but shininess hasn’t been determined by IVs since Gen 2. I found several sources saying that no, it’s not possible to get a shiny through the Pokéwalker.
Yes it should be possible since a shiny is determined by the random IVs (hidden pokemon data). It will be the same chance as normal, 1 in 8192.
But you won't be able to tell until you send it back to the game, because the Pokewalker is monochrome.