secured web services with PKI

[JazzMaan]

I have a web service that I need to secure.

Client has asked me to use PKI based security not SSL.

I cant find any decent examples of how to do so.

Any one that has done so ?

http://www.aspfree.com/c/a/VB.NET/Securing-Web-Services-with-X509-Certificates/

Looks like I need:
Client Private.pfx
Server Private.pfx
Server Public.cer

but i am confused!!!