Custom Front-End Using Multi-Value Parameters on Reports

Hello,
We have developed our own ASP.NET 2.0 (C#) front-end for Reporting Services (SQL Server 2005). The front-end is kind of "generic" in the sense that it looks at all the parameters for any report selected by the end-user and creates a display for the end-user to configure the parameter values. This all works fine, except for one report that has a multi-value parameter.

On the report viewer through Report Manager, this multi-value parameter displays as a drop down list in which you can select one or more parameters by checking the appropriate checkboxes by the values.

So, we need some way to emulate this. Is there a built-in ASP.NET server control that will handle such a situation If so, what

Or, what else can we do to handle a multi-value parameter in our custom app.

Thanks.