Please see my comment to the question — I strongly recommend not to try to consume services on the client side. You should better do it on the server side.
However, in case you have compelling reasons to do so (I doubt it), you can start with
Exposing WCF Services to Client Script[
^] (still based on ASP.NET),
How To Consume WCF Using AJAX Without ASP.NET[
^].
Note the Microsoft comment "This document may not represent best practices for current development". I think this note is very relevant on this page. :-)
—SA