Here is a way. First install REST Starter Kit Preview 2 and reference your project to Microsoft.Http.dll and Microsoft.Http.Extensions.dll
using Microsoft.Http;
string baseAddress = "http://exmaple.com/Service.svc/"; // Service Base Address
string path="exposedUriTemplate"; //the Exposed UriTemplate for your interface
HttpClient client = new HttpClient(baseAddress);
HttpResponseMessage message = null;
//use HttpContentExtensions to create Http Content, can also use HttpContent class
HttpContent content=HttpContentExtensions.CreateDataContract<T>(T item);
//do Http Request and get the response
message = client.Post(path, content);
//other requests : client.Get(path); client.Put(path, content); client.Delete(path)
Hope it can help.
Allen Wang