This tutorial is from Adobe Developer Connection and it shows how to use Flash Builder 4 beta 2 with BlazeDS AMF endpoints. The concepts are simple and if you download and start up the Vancouver build of BlazeDS (here), you can run this. You will have to ensure you have Java installed and configured properly as described in this tutorial. Have fun! This project has to be built from scratch as the source code will have paths specific to my system.