I have been trying to bind a webcombo client side, as the other controls are all working client side and with it running server side I would lose other data.  I have given this a red-hot go and got it working for the initial load, but when the combo needs to be reloaded based on other changes on the page, and the second time around there are no "values" to retrieve.  

                    <td class="EditField" colspan="7">
                        <ISWebCombo:WebCombo ID="wcStock" runat="server" DataMember="Stock" DataValueField="ID" DataTextField="Description" UseDefaultStyle="true" DropDownRows="1000000" Width="232px" BindingOperationMode="ClientBinding">
                            <Columns>
                                <ISWebCombo:WebComboColumn BaseFieldName="Description" HeaderText="Stock" Name="Description" Width="200px" />
                                <ISWebCombo:WebComboColumn BaseFieldName="CategoryDescription" HeaderText="Category" Name="CategoryDescription" Width="120px" />
                                <ISWebCombo:WebComboColumn BaseFieldName="GroupDescription" HeaderText="Group" Name="GroupDescription" Width="120px" />
                                <ISWebCombo:WebComboColumn BaseFieldName="ID" Hidden="true" Name="ID" Bound="false" />
                            </Columns>
                            <LayoutSettings AlwaysShowHelpButton="false" ComboMode="MultipleColumns" AlwaysShowAllRowsOnDropdown="true">
                                <ClientSideEvents OnAfterItemSelected="wcStock_AfterItemSelected" />
                            </LayoutSettings>
                        </ISWebCombo:WebCombo>
                        <asp:RequiredFieldValidator ID="valReqStock" runat="server" ControlToValidate="wcStock" Display="Dynamic" ErrorMessage="Please select a stock item" ValidationGroup="valGrpItems" />
                    </td>

javascript to remove existing data and reload - this does as expected - rows are removed and new rows added, but the ID Value is not readable the second time through :>

function reloadStockItems (jsonItems)
{
    alert(jsonItems);
    var items = eval(jsonItems);
    
    var rows = purchaseOrder.wcStock.GetRows();
    for (var i = 0; rows[i] != null; i++)
    {
        rows.Remove(rows[i], true);
    }
    
    purchaseOrder.wcStock.Values = null;
    
    rows = purchaseOrder.wcStock.GetRows();
    for (i = 0; i < items.length; i ++)
    {
        var stock = items[i];
    
        stock = stock.split('|');
        var newRow = purchaseOrder.wcStock.NewRow(stock[0]);
        newRow.Value = stock[0];
        var cells = newRow.GetCells();
        cells.GetNamedItem("Description").Text = stock[1];
        cells.GetNamedItem("CategoryDescription").Text = stock[2];
        cells.GetNamedItem("GroupDescription").Text = stock[3];
        
        rows.Add(newRow);
    }
    purchaseOrder.wcStock.RefreshValueItems();    
    purchaseOrder.wcStock.UpdateUI();
        
}

function wcStock_AfterItemSelected(controlId)
{         
    purchaseOrder.wcStock.AddInput("SelectedSupplierValue", purchaseOrder.lstDDSupplier.getSelectedValue());
    purchaseOrder.wcStock.AddInput("SelectedStockValue", purchaseOrder.wcStock.Value);  // <----- problem occurs here in that the values are all set to 0.
    purchaseOrder.wcStock.SendCustomRequest();
    return true;
}