The official Japanese Pokémon website has revealed that
Junichi Masuda's Deoxys will be distributed via IR to players of Pocket Monsters Black 2 and White 2 from December 15th, 2012 to December 23rd, 2012 as part of the Plasma-dan campaign. From December 15th, 2012 to December 23rd, 2012 the Deoxys will be distributed at Aeon Mall locations and on December 22nd, 2012 and December 23rd, 2012 at Makuhari Messe as part of Jump Festa 2013 (ジャンプフェスタ2013). Below are the details.
Sources:
http://www.4gamer.net/games/148/G014842/20121210023/ and
http://www.pokemon.co.jp/info/2012/12/121210_g01.html