OK so I was thinking this. You know that the Pokewalker has only infrared which means it can only connect to legitimate copies of HG/SS. I was thinking about it and do you think that it is possible to change it so that it still has the infrared but it also has the WiFi stuff like other DS games have. So this way I could say connect it to my Pokemon HG on my R4i.
Even if you could reverse-engineer the pokewalker to communicate through WiFi, the game is still going to be trying to make an infrared connection. You'd have to hack the pokewalker, the DS itself, and the game ROM to make this possible. Good luck with that.