I was one of those people. My college friend was able to break the chains of my liberal enslavement thru Rush Limbaugh. Helping him unbrainwash his friend is the least I could do. Well, the least I could do is nothing, so I'll go him one further.
Good luck ... But I'm betting your personal experience made you open to reason when Rush came calling. Until that sort of real, live, experience affects a liberal, they're unreachable.
As they say, a conservative is a liberal who's been mugged.