Create Custom Content Type using Client Object Model

I need to create custom content type from a given guid for a SharePoint site using Client Object Model. However, in the constructor of

ContentTypeId ctid =newContentTypeId()

there is no facility to provide value for GUID.

If one notices server side object model to perform the same operation as per http://msdn.microsoft.com/en-us/library/ff798370.aspx then there is an option to provide GUID in the constructor as

SPContentTypeId myContentTypeId =newSPContentTypeId("0x010100FA0963FA69A646AA916D2E41284FC9D9");

Why there is such a difference between Client Object Model and Server Object Model? Is there any possible work around?