I have a XamDataGrid with several bound columns and one unbound column, a radio button column.  What I want to do when calling InitializeRecord is to set the radiobutton as selected for the first record added ( so there is at least one radiobutton selected ).  Here is the style template for the radiobutton:

<Style x:Key="rbInCellStyle" TargetType="{x:Type igDP:CellValuePresenter}">

<Setter Property="Template">             

<Setter.Value>   
<ControlTemplate TargetType="{x:Type igDP:CellValuePresenter}" >             
<RadioButton GroupName="CellButton" HorizontalAlignment="Center" VerticalAlignment="Center" IsChecked="False" Click="RB_Click" />

</ControlTemplate>

</Setter.Value>

</Setter>

</Style>

Inside InitializeRecord, I do this for the other bound columns:

object typeValue = (e.Record as Infragistics.Windows.DataPresenter.DataRecord).Cells["PeakDefType"].Value;

string tempstr = typeValue.ToString();

            (e.Record as Infragistics.Windows.DataPresenter.DataRecord).Cells["TypeAsString"].Value = typeValue;

How do I do something similar for an unbound column?