Change List of Search Engines

I would like change the options listed on the Customize Search Settings dialog page. To get there I click IE | Search | Customize. I am using IE V6.0.2800.1106.

On the Customize Search Settings dialog page, when I check the option Use One Search Engine, 9 choices are displayed. I want to remove three that I never use, and replace them with three search engines I frequently use.

Where is the list stored? How can I edit the list?