One more thing about getting a file from the web/SharePoint and using it as a source in SSIS: If you need to authenticate just change the xml.open command to:
xml.open "GET", URL, false, "user", "password"
where user and password are the user & password that has permissions to the desired file. Note that it is VERY recommended to have an application user, so the password won't be changed in the future. If you don't have such user and you must change your password in the future, do not forget to change it in the script. My tip: add a reminder in your calendar to change the password in the script.
In this point I don't know if you can authenticate using SSL or stronger protocols using VB script.