Drupal 6 AHAH functionality with Pages module?

Hi.

I would like to use Drupal 6 form AHAH functionality. Every example of AHAH i find is showing it's usage from within a module. I need to use it without any modules.
I'm trying to use it inside Pages module where you can add custom content to a page which is normal PHP code. Can someone provide AHAH usage example outside of module?
Hard to explain... I hope it makes seance.