How would one go about submitting data to search engines through a loop.

I.E how do the search engine submission sites do it

Google submitted successfully
Yahoo submitted successfully
Altavista submitted successfully

Etc.

Why would you want to submit directly to the search engines? Getting indexed is as simple as placing an inbound link to your site from an already indexed (and preferably respected) website.

I know how to get indexed, but that isn't why I made the thread. Just really need to know what needs to be done to automate search engine submissions like theses search engine submission sites.