From what I understand, you are attempting to add an event Pokemon via PokeGen in a 4th Gen game.
You can get the Wonder Cards for the Event Pokemon here: http://projectpokemon.org/events/
In PokeGen, set the target game to one of the 4th Gen games (Options > Target Game) and add in the Mystery Gifts (Tools > Mystery Gifts) you want. You can either save this to an existing save that you've loaded, or generate an Action Replay code to use. Then, receive the Pokemon in-game and relocate them to Black.
You cannot transfer a Wonder Card using a GTS Program. You can, however, find a .pkm file from a site such as http://www.pokecheck.org/ and send that.
I also recommend using Shiny2 instead of IR-GTS. http://projectpokemon.org/forums/showthread.php?22310-Shiny2-Distribution-System