You can use the extension manager from dmxzone, I've used it to install also webassist extensions since I use both of them, they also offer a free extension for the server, behavior and bindings panels.
Your friends over here at WebAssist! These Dreamweaver extensions will assist you in building unlimited, custom websites.
These out-of-the-box solutions provide you proven, tested applications that can be up and running now. Build a store, a gallery, or a web-based email solution.