I downloaded the client ecto (for MacOSX) so it would be easier to add entries to this Blog. Unfortunately nothing really said how to configure the Drupal site and ecto.
After some testing/trying, I found it working if the blogapi module in Drupal was set to Movabletype and ecto to have the URL to be https://stupid.domain.name/xmlrpc.php. The URL I figured out by reading the code in modules/blogapi.module code and looking in the log for Drupal for my site.
Of course, I don’t know yet if posting really works, that I will see if this post actually end up in the blog. I was able to fetch blog entries though.