The CTP documentation is up in the vCampus Library, under "vCampus PI Products Kit" and then"Data Access Technologies". The last entry (currently) is "PI Web Services -- Community Technology Preview". If you click that, you get a PDF which you can save locally.
The documentation contains guidance on using the two interfaces and the structures used to pass parameters to the web service and receive data. Just remember the path to the WSDL is different. For that, see http://vcampus.osisoft.com/blogs/webservices/archive/2009/08/25/how-to-access-the-ctp-ws.aspx.