When I configured my blogengine blog to Windows live writer, one site, it worked without giving the meta weblog link, just the URL, username and password only.
But when I tried to configure the http://geekiest.net it asked for the type. So first I gave the Metaweblog API type and what happened finally was the Windows live writer failed to delete the temporary post it created. Then I tried to configure the same blog with the same configuration with just one difference, that was the type I choose was Movable Type API, it worked fine.
the API link will be the Meta web log for me it is /metaweblog.axd