I had the same issue. You need to bind to the DataContext of the DataCell. The following is an example where I only wanted the CheckBox to be visible if another value in the object was true.
<xcdg:Column FieldName="DateActual" MinWidth="40" Title="Actual" Width="40">
<xcdg:Column.CellContentTemplate>
<DataTemplate>
<CheckBox HorizontalAlignment="Center" Visibility="<b>{Binding Path=DataContext, Converter={StaticResource VisibleIfCustomDate}, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type xcdg:DataCell}}}</b>" IsChecked="{Binding Mode=OneWay}" />
</DataTemplate>
</xcdg:Column.CellContentTemplate>
<xcdg:Column.CellEditor>
<xcdg:CellEditor>
<xcdg:CellEditor.EditTemplate>
<DataTemplate>
<CheckBox HorizontalAlignment="Center" Visibility="<b>{Binding Path=DataContext, Converter={StaticResource VisibleIfCustomDate}, RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type xcdg:DataCell}}}</b>" IsChecked="{xcdg:CellEditorBinding}" />
</DataTemplate>
</xcdg:CellEditor.EditTemplate>
</xcdg:CellEditor>
</xcdg:Column.CellEditor>
</xcdg:Column>
Hope this was helpful.