Returning different HTTP error codes from a .net SOAP 1.2 web service

Hi hope someone can help me here, I have developed a SOAP 1.2 web service using VS 2005 and the customer has specified that certain HTTP error codes are returned from this web service when faults occur. I understand that SOAP 1.1 errors were returned as HTTP 500 errors containing a SOAP fault but that in SOAP 1.2 different HTTP errors can be returned again containing SOAP faults.

Anyone know how I can return different HTTP errors, at present if I throw a SOAP exception or HTTP exception then they are returned as HTTP 500 errors.

Thanks