Show and Share uses Basic Access Authentication, a commonly used method that allows a client to provide username/password credentials. You can choose a number of different clients/programming languages to implement this. Using Flash (ie, a swf) is just one of these.
 
There is an example of how to do this for Java using HttpClient3.0 in the Digital Signs section of the forum. The method of authentication is the same for Show and Share: http://developer.cisco.com/web/dms/forums/-/message_boards/message/2177726
 
There are many other clients that you could be using, and we don¿t have examples for all of them. However, since this is a fairly common form of authentication, you should be able to find various resources online that explains how to implement this for the client that you are using.