Thankfully, most popular web frameworks provide some support to accomplish this. Ruby on Rails supports overriding the http method using the X-HTTP-Method-Override request header.
The below code tells the RoR server app to consider the request as a PUT operation:
var request:URLRequest = new URLRequest(resource);
request.data = dataToUpdateOnResource;
request.method = URLRequestMethod.POST;
var loader:URLLoader = new URLLoader();
HTTP DELETE can be achieved using the same.