Hey Superpac,
Ian is correct in this. You will set up a list of letters, each linking to the search page with a URL parameter ( yourpage.php?filter=a ). Create a search page with a recordset of all page titles and a URL parameter named the same as the one linked on the search page ( this is configured in the Bindings panel ). From there you enter the DataAssist search wizard and set up a Search Comparison as Advanced Text Search and finish the Wizard. Next, open the DataAssist Search server behavior on the search page. Change the trigger to before page load, and edit the search filter in the search filter list. Change the comparison to Begins With and change the value to the URL parameter created earlier.
That should do it.
If you have trouble, please let us know