Create Json Array with ServiceStack

Quite new to .NET. Still haven't gotten the hang of how to do dictionaries, lists, arrays, etc.

I need to produce this JSON in order to talk to SugarCRM's REST API:

{
    "name_value_list": {
        "assigned_user_name": {
            "name": "assigned_user_name",
            "value": "joe"
        },
        "modified_by_name": {
            "name": "modified_by_name",
            "value": "jill"
        },
        "created_by_name": {
            "name": "created_by_name",
            "value": "jack"
        }
    }
}

from this C# POCO, which plays nicely with ServiceStack:

public class lead {
    public string assigned_user_name { get; set; }
    public string modified_by_name { get; set; }
    public string created_by_name { get; set; }
}

I have to do this sort of conversion for lots of different classes, so I don't think it's wise to create another strongly typed class (ala Costomising the serialisation/serialised JSON in service stack)

I've looked through the ServiceStack docs, but maybe I missed an example of this somewhere.

How do I build this JSON in a way that I can extend to other ServiceStack POCOs?