Update - following a response from the developer the AHP extension now works in ArcMap 9.2.
When I tried to install the extension I was getting a message saying "No new objects added".
To install the extension you have to install it in administrator mode. Right click the ArcGIS icon and select "Run as
admin...". The extension should then be available in the "Developer tools" section. Go to menu Tools -> Customize.
Go on the second tab. Scroll down the list on the left hand side until you see "Developer samples". Click on this item.
On the right hand side you would see a text that says "AHP...". Click on that item and drag it to an ArcMap toolbar.
Then close the window and the extension should be ready for use.