Accessing Drupal from external website

Hi everybody, I have a Drupal system which has a heavily customized search engine. I would like to offer the search as widget for Wordpress. We've successfully created the code (blog.planetabroad.com -> right hand) and it works great as long as the wordpress installation is on the same server as Drupal (because I have to include bootstrap.inc so I use chdir($drupal_path));

Now - the question is how can I get this widget to work from other peoples' servers? I tried creating a php script which just includes bootstrap.inc and calls drupal_bootstrap but even for that I have to be on the same server in order to properly include it.

Any ideas/comments/links?

Thank you very much in advance.

Jonas