Registered in live.com and search for live webmaster tool (IMO, it is a clone of google webmaster tools) . Then you can submit your site there .
don't bother, why you bother submitting your site in MSN, just build some backlinks and the main search engines will get indexed your site pretty quickly.
It is always better to SignUp for Live Webmaster Account for the website and then submit though your Live Webmaster Center.