Edit User Role GridView

I would like to be able to have the ability to edit a role information inline in a gridview.  Currently have the simple code setup to display all the users (although would like to limit it to not include Administrators) with
...Page Load... GridView1.DataSource = Membership.GetAllUsers() GridView1.DataBind() End Sub I would like a multi-select listbox in-line in the edit template of the gridview, I am sure this is possible but just drawing a blank on how to achieve this.  I understand the basics of putting a template field in the grid and putting a listbox inside the edititemtemplate but not sure where to go from there...
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