Workaround for returning IDictionary-like collections from webmethod?

Question

Problem is very well known - you can't return collection from web method that implements IDictionary. I'm not looking for a way to serialize IDictionary in xml.

How do you work around this in .net 2.0?

I need to return a collection from web method that looks like:

Key, String value Key, String value Key, DataTable value

So I would need something that is capable of having value as object type.

I've tried using KeyValuePair(Of String, Object) but upon web method return, I'm stuck with KeyValuePairOfStringObject() and I can't figure out what to do with it.

So far, I think that two column DataTable is the only viable solution...