Can you get a blaziken from the dreamworld with the ability speedboost?
Nope, only way is by PokeGen, PokeSav, or other hacking materials. However, Nintendo may release it in the future.
You can't get a Blaziken from the Dream World,but if you happen to live in Japan and have purchases the new Pokémon BW TCG Starter sets on October 29th 2010,A password would have been given to you to get 1 Hoenn Starter with it's Dream World ability. Here is the source.