@kajik I know that this post is suppost to be dead and nearly finished, but a user by the name of Flame actually found a Japanese DSi with the missing DSi + Internet TMD (00030004/4b32444a).
Here it is, we're almost there!
https://mega.nz/#!ocAiBKjD!tYcOl06cVyxfjRTFCmd12JtmMbzqbE0CY6wXp81RRAw
In the interests of preservation, is this file still available anywhere? The Mega link is dead.