Use the DataBinder method. The code may look similar to:
<ig:TemplateDataField Key="CheckBox">
<ItemTemplate>
<asp:CheckBox ID="CheckBox1" runat="server" AutoPostBack="true" OnCheckedChanged="Checkbox1_CheckChanged" checked='<%# DataBinder.Eval(CType(Container, Infragistics.Web.UI.TemplateContainer).DataItem, "CheckBox") %>'/>
</ItemTemplate>
<Header Text="CheckBox" />
</ig:TemplateDataField>