If you're downloading an xsiaddon, extract and install like any usual Softimage addon: Softimage -> File - > Addon -> Install Addon. If you're grabbing the addon folder from a zip file, just plop it in your workgroup or user root.

TCPServer_For_Softimage menu entry is stored in View -> TCPServer -> TCPServer Preferences.

This fork has been modified to work in Softimage running in Linux, which is unfortunately stuck in Py2.5 from versions 2013 and below.