DataBind ListBox w/ Hashtable-objects

Ok, I get the following:

myHT.Add("key1", "value1");
myHT.Add("key2", "value2");

lb.DataSource = myHT;
lb.DataTextField = "Key";
lb.DataValueField = "Value";
lb.DataBind();

Works fine.
Now, I want to do the same kind of thing, except that the Hashtable will store objects instead of simple strings:

obj1.Name = "myName1";
obj1.Value = "myValue1";
obj1.Tag = "myTag1";
obj2.Name = "myName2";
obj2.Value = "myValue2";
obj2.Tag = "myTag2";

myHT.Add("key1", obj1);
myHT.Add("key2", obj2);

lb.DataSource = myHT;
lb.DataTextField = "Key";
lb.DataValueField = "Value";
lb.DataBind();

...only I want to do something akin to:

lb.DataValueField = "Value.Tag";

a) obj's must be [Serializable] - check.
b) overriding obj.ToString() to return _tag; will work

I just want to know, how can one force a list box in data binding to utilize the object properties the 'correct' way?
Any ideas?

Thanks,