Take a look at the ContactMine sample application. The Contact Type Management screen populates a list with values from the database and then acts on the selected values. It does not allow multiple selection, but for that all you need to do is add the MULTIPLE attribute to the SELECT element. The documentation of the Request object explains how to access form data in such cases. Of particular interest will be Request.FormCount with the optional cFormVar parameter and Request.Form with the optional nIndex parameter.