I am a dork; for reference, here is what you can do:
public static MyClass CreateInstance(CSharp.Context context,
OtherClass node)
{
var globalPrototype = context.GetGlobal("MyClass");
var prototype = globalPrototype.Unbox<CommonObject>();
return new MyClass(context.Environment,
prototype.GetT<CO>("prototype")) { Node = node };
}
which will return an instance of MyClass that itself contains a
property called Node that is an instance of OtherClass.