The transfer between SoulSilver and Black does not require the services that were disconitnued by Nintendo. You can transfer up to 6 Pokemon (that don't know HMs) at a time to Black through DS download play, by putting SoulSilver in one DS, and Black in the other. In the Pokemon Transfer Lab on Route 15 in Black, talk to the man inside to get your transferred Pokemon through a minigame.
For more information, refer here.
