How to set the value for dropdownlist of AJAX autocomplete?

Question

Hi,
I am using Microsoft AJAX autocomplete to lookup some product from database. I am wondering if it's possible to access onSelected event of the dropdownlist. Actually, what I want to do is only display product name in dropdownlist, and keep product ID in value field of the dropdownlist. When a user select an item from the dropdownlist, I will retrieve the product ID from the dropdown control for futher action. But since the webservice only return one string and that string is populated into dropdownlist automatically. I couldn't find how to set the text and value for dropdownlist using diffrerent values....
Did anyone have idea how to achieve it?
Any help would be really appreciated!
Thanks!