BuddyPress.org

I am now going through the How to Write a WordPress Plugin tutorial on DevLounge.net.

It says you can hook into WordPress to execute pieces of code using WordPress actions. I assume in my case I should use this action:

register_post

So I should write a function that somehow forms and executes that URL – http://mysite.com/…/listmessenger.php?etc. – and trigger that on registration using register_post?

And to construct the function I can use WordPress filters? The available ‘database writes’ filters are only for WordPress tables of course…

How would I add data to tables outside WordPress, in this case the ListMessenger tables?

Edit 1: Stupid question; that is done by that URL created by $post_data=… in the PHPList code.

Or is there a better way to add data to the database directly from the plugin?

Edit 2: This page has more information on creating/updating tables outside regular WordPress. Would that approach be better than that URL?