Hi all

the text below came from the following link: http://www.fantasyflightgames.com/edge_news.asp?eidn=4550

With his skills for removing your opponent’s character agenda, Vargo Hoat may seem like the perfect leader of your Mercenary company, but you may want to consider another key character in The Tattered Prince (A Journey’s End, 117). Not only will The Tattered Prince allow you to play out-of-house Mercenary characters without penalty, he also lowers the cost of the first Mercenary character you play. The Tattered Prince can help you get your characters into play and a character like the Gold Cloaks (A Time of Trials, 25) establishes reliable draw. Soon, you can be well on your way to establishing a deadly Mercenary host, full of powerful characters like Shagwell and Vargo Hoat.

and my question is, how can I play House only X characters using a Neutral faction or Another house?

thanks

and my question is, how can I play House only X characters using a Neutral faction or Another house?

You can't.

Other than the City of Shadows agenda, there really aren't any card effects that allow you to ignore "House X only" restrictions when building your deck. The Gold Cloaks/Tattered Prince draw engine described in the article assumes your "Mercenary" deck is built out of House Lannister.