The "Sitemap Generator" provided by Google is a console script written in Python and is intended to be executed on the console to generate the sitemap.
Unfortunately, this is not supported with our service because:
Python is not installed on our server Unlike in UNIX host, it is not possible for customer to execute shell command on our server.
The Sitemap file is just a simple text file that follows several formats (OAI-PMH v2.0, RSS 2.0, Atom 0.3).
According to Google, it is possible that you can write your own program to generate the needed sitemap file. See https://www.google.com/webmasters/sitemaps/docs/en/protocol.html
Alternatively, there are a number of freely available services/tools to generate a Sitemap file. For example, we have found these: