From Rockford Lhotka's Expert C# 2008 and VB 2008 Business Objects books
Andy,
I have done this two different ways with one or two multi-select list boxes. It depends on what you are trying to show the user.
For 1 listbox, the datasource is the BO property. You then create a 2nd BO property which is a List(Of String) which holds the selected values. In the UI you need to write a bit of code to process the selected values, add them to a List(Of String) and then store that list in the BO. You also need to add a bit of code to populate the list box when the user returns to the page and then run over the list of selected values and re-select them for the user.
For 2 listboxes where you move one from the Available list to the Selected list - it can be done but is a real pain in the ***. See if 1 listbox works for you!
Joe