Seaside was first delivered as part of the VA Smalltalk V8.0 release. You can download the latest VA Smalltalk release from the Instantiations download site at http://www.instantiations.com/VAST/download/. After installing VA Smalltalk, start the development image.
Seaside support is provided as a loadable feature in VA Smalltalk. From the Transcript, select Tools | Load/Unload Features... to open the Feature Loader, see Figure 42.
Scroll down to the ST: Seaside Core feature, select it, and use the >> button to mark it for loading. You can see other Seaside features in the list that you may also want to load. When you have selected all the features you want to load, and have moved them to the Loaded features list, select the OK button to load the features into your image.