Hi,
you can solve this problem by using Ajax.
For instance you can use the Ajax-JSF-Solutino from J4Fry.
http://www.j4fry.org/jsfAjax.shtml On every onKeyDown-event you initiate an ajax-request. You have got an select-List with many Items that are updated by the ajax-util. With the attributes "preJSFunction" and "postJSFunction" you can show and hide the select-box.
But there are any other components which have auto-suggestions e.g. ice-faces.
mfg alex