How to pass gridview button commandargument to jquery dialog

In an asp.net 3.5 website I have a gridview with an imagebutton on each row. The imagebutton onclick opens a jquery dialog.

How can I pass the imagebutton commandargument to the jquery dialog to be stored there in a hidden field?

Any help would be much appreciated.

Basic code is as follows:

<asp:GridView ID="dgMap" runat="server" AllowSorting="True" AutoGenerateColumns="False"........................

  <asp:TemplateField>
            <ItemTemplate>
                <asp:ImageButton ID="imgbtnViewDialog" runat="server"  ImageAlign="Middle" ImageUrl="~/images/copy.gif" CommandArgument="<%# Container.DataItemIndex %>"
    CssClass="imgbtnViewDialogClass" />
            </ItemTemplate>
        </asp:TemplateField>

...............</asp:GridView>

'CSS to open jquery dialog:

    $('.imgbtnViewDialogClass').click(function () {
              $('#dialog-form').dialog('open');
              return false;
          });