After almost one month of the Live Search URL Submission form being down, it is now back up at http://search.msn.com/docs/submit.aspx.
Our URL submission page is still http://search.msn.com/docs/submit.aspx
But he didn't seem to realize it was down when he said that. So soon after, it appears Microsoft fixed the URL submission form.
Honestly, I am not sure how often a search engine uses the URLs they obtain from a URL submission form to find new pages. The form being down at MSN for about a month, might be proof of that. But it is now live and you can submit URLs, if it makes you feel better.
Again, the best way to have any search engine find your pages is through links on pages that they already have indexed.