Set culture for dateformat ect on ReportExecutionServiceSoapClient.Render

Hello,

How do I set the culture for the Render call on the ReportExecutionServiceSoapClient. I am using the service call to create  a pdf but all my dates is being rendered as en-US. I would like to render with different cultures depending on a parameter. 

The only parameter with smells like culture is the parameterLanguage parameter on the SetExecutionParameters method, but that is only controlling the format of the parameters.

I works fine both in the browser and in the report viewer control.

Thanks

Henrik.