how do you configure file layout for field: attribute?

My problem is that I want to use the file layout to group all member in my class if they are a DataMember that should be serialized. I have done this successfully for both properties and fields. I.e.

    [DataMember(Order = 0)]
    public List<int> Values { set; get; }

    [DataMember(Order = 1)]
    public List<int> _val;

However I want to be able to sort properties whose hidden backing fields are DataMembers. I.e.

    [field: DataMember(Order = 2)]
    public List<int> MoreValues { set; get; }

Does anyone know how this is done?